Week 28: Cash-Secured Puts — Getting Paid to Bid Lower

---

1. Why This Is Important

A cash-secured put (CSP) is the most honest trade in retail options. You set aside cash equal to the full purchase price of 100 shares, you tell the market "I will buy this stock at $X if it ever trades there in the next 30 days," and the market pays you a few hundred dollars for leaving that bid sitting on the screen. If the stock falls to your level, you buy it — at exactly the price you wanted, minus the premium. If it does not, you keep the cash and write another one. There is no leverage, no naked exposure, no fancy theory. It is a limit-buy order with rent attached.

Most retail traders meet CSPs through bad influencers who pitch them as a yield-farming machine — "earn 30% annualized on your idle cash!" That framing is broken. The right framing, the one Horace uses in this lesson, is CSPs are how you bid on stocks you already want to own. The premium is not your edge. The discount-to-where-you-actually-wanted-to-buy is your edge. If you find yourself selling puts on stocks you would refuse to take delivery of, you are no longer running CSPs — you are running a casino with extra steps, and the dealer eventually catches up.

Four reasons this lesson matters:

1. CSPs are the cleanest way to express patience. Markets reward investors who can wait. Most retail investors cannot — they buy when CNBC is loud and freeze when the screen is red. A CSP locks in your discipline. The strike is your patience price. The 30-day expiry is your timeout. The premium is your reward for not chasing.

2. They convert idle cash into yield without taking equity risk you didn't already plan to take. If you were going to keep $20,000 ready to buy SPY at a 5% pullback anyway, you can do exactly that and collect $200-$400/month while the cash waits. The cash itself stays in T-bills earning around 4% (April 2026). The put premium is an additive layer, not a replacement.

3. Most CSPs you'd actually want to be assigned. This is the single insight that separates serious CSP sellers from yield-chasers. A CSP is structurally a "limit buy at strike, with a rebate." If assignment scares you, you sold the wrong put on the wrong stock. The barbell puts CSPs squarely on the safe end — they are how you accumulate the boring index/quality positions that anchor a portfolio. You are not trying to avoid assignment; you are trying to price it.

4. They live cleanly inside the options-tax doctrine. Like covered calls, CSP premium income is short-term capital gain regardless of how long you held the contract. That makes CSPs a tax-disaster in a taxable brokerage account if you run them at scale, and a beautiful tool inside a Roth or traditional IRA where the short-term character vanishes. Same rule we hit in Week 27: option income lives in tax-sheltered accounts. Stocks-you-want-to-own live anywhere.

This is a doer's lesson. By the end of it you should be able to look at SPY at $560, decide you'd happily own it at $530, find the 30-delta put that strikes near $530, and know within ten seconds whether the premium is worth the capital lockup.

---

2. What You Need to Know

2.1 The Mental Model: A Limit Buy With a Rebate

Stop thinking "sell a put." Start thinking "resting limit-buy order, paid to stay on the book."

A regular limit-buy order at $530 on SPY does nothing for you. It sits there. If SPY trades to $530 your order fills; if not, it cancels at the end of the day and you do it again tomorrow. You pay nothing, you earn nothing.

A 30-day cash-secured put at the $530 strike is the same buy intention with three modifications:

The order stays alive for 30 days, not one day.

You commit the cash up front — it cannot be used for anything else until the put expires or you close it.

Someone pays you a premium for taking on that 30-day commitment.

That is it. The premium compensates you for two things the regular limit order does not give the market: a time commitment (you can't cancel without buying back the contract) and a firm floor under price (you must take delivery at the strike if it trades through, even if the stock is much lower).

The first commitment is real but small in dollar terms. The second is the one that matters: you are short volatility. If SPY goes to $400 in a crash, you still buy at $530 — and the market knows this, which is why VIX-rich environments pay much more premium than calm ones. The vol tail wags the equity dog directly here: the price you get for a CSP is not really about your stock thesis, it is about how scared other people are about the next 30 days.

The image above shows the annualized premium yield on a 30-day SPY-like put as a function of strike-delta, computed from Black-Scholes with sigma = 22% and r = 4%. The bars climb steeply as you move closer to the money: the 50-delta (at-the-money) put pays roughly 6x the annualized yield of a 10-delta put. But that 50-delta put has a ~50% chance of finishing in-the-money. The yield is not free; it is the probability of assignment, dressed up.

2.2 Strike Selection by Delta

Delta in this context approximates the option's probability of finishing in-the-money. A 30-delta put has roughly a 30% chance of being assigned at expiry, and (loosely) sits around 5% out-of-the-money for a 30-day contract on a normal-volatility stock.

Three working presets, each tied to a temperament:

30-delta CSP (standard):
About 5-7% out-of-the-money for 30-day, sigma=22%
~30% assignment probability
Highest premium of the three presets
For: investors who actually want to accumulate the stock


16-delta CSP (one standard deviation):

About 9-11% OTM, ~16% assignment probability
Roughly half the premium of the 30-delta
Sweet spot for most beginners — your bid is far enough below

    the market that assignment feels like a real bargain


10-delta CSP (conservative):

About 13-15% OTM, ~10% assignment probability
About one-third the premium of the 30-delta
For: investors who view the put as pure rent on cash and would

    only welcome assignment in a meaningful drawdown

Beginners almost always start with the 30-delta because the premium is largest and the temptation is to maximize income. This is the single most common mistake in retail CSP-land. The 30-delta put on a stock you do not really want to own is not income — it is a loaded coin flip where heads pays $200 and tails costs you $5,000. Start at 16-delta and only move closer when you have a stock and price you are eager to be filled at.

2.3 Tenor: Why 30-45 Days

Theta (time decay) is non-linear. In the last 30 days of an option's life, decay accelerates sharply. From 60 days out to 30 days out, a put loses roughly 30% of its time value; from 30 days to expiry, it loses the remaining 70%. As a seller, you want to be camped in the steep part of the curve.

Tenor          Premium    Daily Theta    Annualized Yield-on-Cash

=========      =======    ===========    ========================
7 days         lowest     highest        very high (but unstable)
14 days        low        high           high
30 days        medium     medium-high    sweet spot
45 days        higher     medium         sweet spot
60 days        higher     lower          mediocre
90 days        highest    lowest         poor

The 7-day weeklies look attractive in spreadsheets — you're rolling four times per month, theta is screaming — but the realized P/L is brutal because gap-risk is concentrated. One earnings miss or one Fed surprise inside that week, and you eat a full month of premium in a single move. The 30-45 day window is where the decay/gap-risk tradeoff is best for retail, and it happens to match the natural monthly options expiration cycle.

2.4 Capital Cost — The Hidden Half of the Yield

Every CSP locks up cash equal to (strike x 100). That cash is not dead. Inside any modern broker (IBKR, Fidelity, Schwab as of April 2026), the cash collateral on a short put earns one of:

• T-bill yield in a money-market sweep (~4.0%, April 2026 SOFR)
• Margin-account credit interest (varies)
• A government MMF position the broker permits as collateral

So the total yield-on-cash for a CSP is:

Total yield = T-bill yield (cash collateral) + put premium yield (option)

~= 4.0%/yr + (premium / strike) * (365 / DTE)

A 30-day, 16-delta SPY put yielding 0.4% in premium therefore returns roughly 4.0% + 0.4% x 12 = 8.8% annualized on a no-assignment cycle. This is the number you compare against. It is not 4.8% (premium only, ignoring cash interest), and it is not 30%-something (annualizing the premium without subtracting taxes and assignment cost). Always quote yields including the T-bill leg.

This matters for the regime you live in: in the 1990s when T-bills paid 0%, CSP yields looked huge by comparison. In 2026 with T-bills at 4%, the incremental yield from selling puts is the only thing worth measuring, and it is much smaller than uninformed YouTubers claim.

2.5 Rolling and Defending — Rules, Not Vibes

A put is "threatened" when the underlying drops to (or below) your strike with significant time left. You have four moves at any moment:

Do nothing — accept assignment. This is correct if you genuinely want the stock at the effective price (strike - premium). It is the default answer for index CSPs.

Buy to close at a profit. Once the put has lost 50-70% of its premium with significant time left (typically before the last 7 days), close it. You have captured most of the theta; the remaining premium is not worth the gamma risk.

Roll down and out. If assignment looks likely but you still don't want the stock at this strike, buy back the threatened put and sell a new put at a lower strike, further dated, for a small net credit. You have moved your bid lower and bought time. Do this at most once or twice — endless rolling turns CSPs into a pyramid scheme of deferred losses.

Take the L and close at a loss. If your thesis on the stock has changed and you no longer want to be assigned, close the put at whatever loss the market gives you. Cash-secured puts have bounded losses (strike x 100 is the worst case), but bounded does not mean small.

Defensive playbook (mechanical version):

Trigger                              Action
=================================    ===============================
Put at 50% of max profit, >7 DTE     Buy to close, redeploy
Put at 80% of max profit             Always close
Stock at strike, 14+ DTE             Hold; let it work
Stock 5% below strike, 7 DTE         Decide: take assignment or roll
Stock 10% below strike, any DTE      Take the assignment unless thesis dead
Earnings inside the contract life    Avoid in the first place

Notice: there is no rule that says "double down" or "average into a losing put." Selling another put at the same strike when the first one is underwater is doubling exposure to a stock that the market disagrees with you about. The market can stay below your strike longer than you can stay willing to wear the loss, especially if you keep adding — irrationality outlasts solvency more often than the spreadsheet admits.

2.6 Assignment Psychology — You're Buying, Not Losing

For most retail CSP traders the panic moment is the morning after assignment, when 100 shares of stock appear in the account at a price that is now above the market. The mental frame matters here.

Assignment is not a loss event. It is the buy order you placed 30 days ago, executing exactly as designed.

If your 16-delta SPY $530 put was assigned because SPY closed at $528, you bought 100 shares of SPY at $530, pocketed $300 in premium for the trouble, and your effective cost is $527 — better than the market price the day you wrote the put, better than the market price the day you were assigned. You executed your patience plan exactly. The only loss scenario is if you panic-sell those shares the next day at $520. The shares are not the loss; the panic is.

The right next move after assignment is almost always to start writing covered calls on the assigned shares — Week 27's playbook. The wheel (CSP -> assignment -> covered call -> call-away -> CSP) is the natural cycle. You bought the dip and now collect rent on the way back up.

The only stocks where assignment is genuinely bad are the ones you should not have written CSPs on in the first place: meme stocks, single biotechs, leveraged ETFs, anything you would not buy outright at the strike.

2.7 PUTW: The CSP Strategy as an ETF

WisdomTree PUTW (CBOE S&P 500 PutWrite Index Fund) is the institutional version of this lesson. It mechanically sells 1-month, ~2% out-of-the-money SPX puts, fully cash-secured, every month. It exists to settle the question "does systematically writing puts beat just owning the index?"

The chart shows cumulative growth of $1 invested in PUTW vs SPY from January 2016 to December 2024. The numbers (April 2026 vintage):

• PUTW: ~7% per year, max drawdown about -22% in March 2020
• SPY: ~12% per year, max drawdown about -34% in March 2020

PUTW captured the put premium consistently and weathered 2018, 2020, and 2022 with smaller drawdowns than SPY. But in the 2017, 2019, 2021, and 2023 melt-ups, the cap on upside is structural: the put premium is a few percent per month, but SPY can rip 5%+ in a month and PUTW only collects the put premium, not the underlying gain. Over a full cycle PUTW lags SPY in total return, lags more in bull years, and outperforms only in flat or modestly down years.

The takeaway: systematic CSP-writing is real, defensible, and inferior to plain index ownership in a normal expansion. The reason a thoughtful investor still does CSPs is not to beat SPY on total return. It is to (a) build cash positions into specific names you want to own, (b) generate income inside an IRA where the tax drag of the equivalent stock-trade strategy would be worse, and (c) lower portfolio volatility while accepting a modest return drag.

If you are tempted to think "PUTW lags SPY -> CSPs are bad," you have misunderstood the trade. PUTW is mechanical, indiscriminate, and pays a fixed expense ratio. Targeted CSPs on stocks you want to own at prices you want to own them at are a different animal.

2.8 Tax Treatment — Same Rule as Week 27

Premium from short puts is short-term capital gain when the option expires worthless or is bought to close, regardless of how long the put was open. There is no long-term holding-period exception.

Outcome                         Tax treatment

============================    ==============================
Put expires worthless           STCG on full premium received
Put bought to close at profit   STCG on (received - paid)
Put bought to close at loss     STCL (offsets STCG/long-term gains)
Put assigned -> stock taken     Premium reduces cost basis of the
shares; holding period for the
shares starts on assignment day

In a taxable account at a 35-37% top bracket, a CSP yielding 5% per year in premium is netting ~3.2% after tax. Inside a Roth IRA, it's netting 5%. The entire short-vol toolkit only makes sense in a tax-sheltered wrapper for high earners. In a regular brokerage, you are running options strategies for the IRS's benefit.

The interactive below walks the math for any combination of underlying, delta, and DTE in real time.

[INTERACTIVE: interactive/week28_put_writer.html]

---

3. Common Misconceptions

"CSPs are free money / yield-farming." They are not. The premium is the market's price for taking on a defined drawdown risk. Annualizing 30-day premium and quoting "30% yield!" hides the fact that the realized yield includes the assignment outcomes, which are negative when they happen.

"You should never let a put get assigned." Backwards. On a stock you want to own, assignment is the intended outcome. Aggressively rolling away from assignment on every dip turns a buy-the-pullback strategy into a perpetual-rent strategy that eventually catches a 20% drop you can't roll out of.

"30-delta is the standard, so I should sell 30-deltas." 30-delta is the standard for a reason — the premium is meaningful — but only on names you genuinely want to own. On an index where you would happily accumulate at any pullback, sure. On a single stock you are lukewarm about, 16-delta is more honest.

"Selling weeklies is more profitable because you do it 4x as often." Daily theta is highest in the last 7 days, but so is gamma. Weekly puts get destroyed by single-day gaps far more than monthlies, which is why systematic put-writers (including PUTW) almost always sell ~30-day, not 7-day.

"PUTW lags SPY, so CSPs are useless." PUTW is a mechanical indiscriminate seller of OTM SPX puts. A thoughtful CSP program is targeted, opportunistic, and used to acquire shares — not to maximize total return. They are different products solving different problems.

"The put premium is my profit." The premium is your gross income. Your profit is premium net of (a) the cost of capital tied up in collateral, (b) the realized losses from assignments at strikes above market, and (c) taxes. Most retail CSP traders track only the premium and are confused by their account balance two years in.

"Cash-secured means there's no risk." Cash-secured means you cannot lose more than (strike x 100) per contract. That is bounded risk, not zero risk. A $530 SPY put has $53,000 of capital at risk if SPY goes to zero. Bounded does not equal small.

"I can just roll forever if it goes against me." Rolls work for one or two cycles and only against shallow moves. In a real correction (2008, 2020, 2022) put strikes get blown through so fast that the rolls keep moving lower without ever recovering, and you end up with the original loss plus several months of additional theta you paid to defer it.

"Selling puts is the same as buying stock at the strike." Almost, but not quite. The put seller does not benefit from upside above the strike. The stock buyer does. This is why CSPs in a melt-up market lag long stock by exactly the missed upside.

"IV crush is good for me." Yes, if you are already short the put. But the implication that you should write puts whenever VIX is high is dangerous — VIX is high because realized vol is also high, and your put is more likely to be assigned. The right framing is "premium is fairly priced; sell what you actually want to own."

---

4. Q&A

Q1. How much capital do I need to start running CSPs? At least enough to cover 100 shares of one underlying you want to own. For SPY at $560 that's $56,000 per contract. For KO at $70 that's $7,000. Beginners should start with one underlying, one contract, and an account size where one assignment doesn't dominate the portfolio — a rough rule is no contract should require more than 10-15% of total portfolio cash.

Q2. How is a CSP different from a naked put? Mechanically the option position is identical. The difference is the collateral. A cash-secured put has 100% of the strike-exposure in cash. A naked put uses margin — you might post only 20-25% of the notional, leveraging 4-5x. Naked puts magnify both income and assignment risk; they are not a beginner trade and not what this lesson covers.

Q3. What underlyings work best? Liquid index ETFs (SPY, QQQ, IWM), large-cap quality names you would actually own (AAPL, MSFT, KO, JPM, BRK.B), and ideally with weekly+monthly options chains. Avoid: single-name biotech, recent IPOs, stocks under $20, leveraged/inverse ETFs, anything with binary catalysts inside the contract life.

Q4. Should I avoid earnings? Generally yes for single names. Earnings inflate IV and pay you more premium, but they also inflate the gap risk. Selling a put through earnings is a directional bet on the earnings reaction — fine if you actually wanted that bet, dangerous if you thought you were collecting "rent." Index CSPs don't have this problem (no single earnings).

Q5. What if the stock gaps below my strike overnight? You take the assignment at the strike. Your effective cost is still (strike - premium), and you bought 100 shares at exactly the price you committed to 30 days ago. Yes, the market is now below that, which is uncomfortable, but it is not different from your original plan. Either you wanted the stock at that price or you didn't.

Q6. Can I sell CSPs in a margin account? Yes, and most modern brokers will route the cash collateral to a money-market sweep so it earns T-bill yield while it's tied up. You can also sell naked puts in a margin account, which is different — see Q2.

Q7. How do CSPs interact with the wash-sale rule? If you take a loss on shares and within 30 days sell a put on the same security with a strike close to the original purchase price, the IRS may treat it as a wash sale and disallow the loss. The exact line depends on facts and circumstances. Consult a tax pro if you are running CSPs alongside loss-harvesting on the same names.

Q8. Is there any scenario where a CSP outperforms just buying the stock? Yes — flat or modestly down markets. If SPY ends the month exactly where it started, the long-stock holder made $0 and the CSP-seller made the full premium. If SPY drops 1%, long stock is down 1% and the CSP-seller is up roughly (premium - 1%). In strongly up markets (above strike + premium) long stock wins; in strongly down markets both lose, with CSP losing slightly less by the premium.

Q9. Why is the 30-day implied volatility relevant when I only care about the premium? The premium is the IV — Black-Scholes with everything else fixed maps premium to vol one-to-one. When you compare CSPs across names, you are implicitly choosing which IV you are short. Higher IV = higher premium = higher realized vol = higher chance of assignment. There is no free yield-arbitrage here.

Q10. What's a sensible starting cadence? One contract per month per underlying you want to accumulate, on a 30-45 DTE 16-delta strike. Re-evaluate after 6-12 months. The point is not to maximize the number of trades; it is to systematically accumulate target positions at target prices while collecting incremental yield.

Q11. Do I need to actively manage these or can I let them expire? You can let them expire if your thesis hasn't changed and the put is far out of the money near expiry. The half-decent rule is: if at 7 DTE the put has lost 80%+ of its initial premium, just close it for the small remaining cost — you free up capital and remove gamma risk for the last week.

Q12. How does this fit into the barbell? CSPs on index ETFs and quality compounders are unambiguously safe-end activity. They build positions you wanted anyway, pay you to wait, and have bounded downside. CSPs on volatile single names with binary outcomes are speculation-end activity. The mistake is mixing the two — using safe-end framing to justify selling 30-delta puts on a meme stock. Separate them in your head and in your account.

30-delta現金擔保認沽期權（標準）：
30天、sigma=22%時，約價外5-7%
約30%接貨概率
三個預設中期權金最高
適合：真正想積累股票的投資者


16-delta現金擔保認沽期權（一個標準差）：

約價外9-11%，接貨概率約16%
期權金約為30-delta的一半
大多數初學者的最佳選擇——你的買盤距市場足夠低，

    接貨感覺是真正的便宜貨


10-delta現金擔保認沽期權（保守）：

約價外13-15%，接貨概率約10%
約為30-delta期權金的三分之一
適合：把認沽期權純粹視為現金租金的投資者，

    只在重大回撤時才樂意接貨

到期期限      期權金      每日Theta      現金年化收益率

=========     =======     ===========    ========================
7天           最低        最高           很高（但不穩定）
14天          低          高             高
30天          中          中高           最佳選擇
45天          較高        中             最佳選擇
60天          較高        較低           一般
90天          最高        最低           差

總收益率 = 國債收益率（現金抵押） + 認沽期權金收益率（期權）

~= 4.0%/年 + （期權金 / 行使價） * （365 / 到期天數）

防守操作手冊（機械版）：

觸發條件                              行動
=================================    ===============================
認沽期權達最大利潤的50%，>7天到期      買回平倉，重新部署資金
認沽期權達最大利潤的80%               必定平倉
股票在行使價，距到期14天以上           持倉；讓它自行發展
股票低於行使價5%，距到期7天            決定：接貨還是滾倉
股票低於行使價10%，任何到期日          接貨，除非論點已死
合約有效期內有業績公佈                 一開始就避免

結果                              稅務處理

============================      ==============================
認沽期權到期一文不值              全額期權金收入的短期資本增值
以盈利買回平倉                    （收取金額-支付金額）的短期資本增值
以虧損買回平倉                    短期資本虧損（可抵銷短期/長期資本增值）
認沽期權被執行→接貨股票           期權金降低股票的成本基礎；
股票的持有期從接貨日開始計算

30 Delta CSP（標準型）：
30天期、波動率22%情況下，約5至7%價外
約30%的執行機率
三組預設中權利金最高
適合：確實想要累積該股票的投資人


16 Delta CSP（一個標準差）：

約9至11%價外，約16%執行機率
權利金約為30 Delta的一半
多數初學者的最佳切入點——出價距市價夠遠，

    被執行時真的感覺是撿到便宜


10 Delta CSP（保守型）：

約13至15%價外，約10%執行機率
權利金約為30 Delta的三分之一
適合：將賣權視為現金純粹租金的投資人，

    只在出現顯著回撤時才歡迎被執行

期限          權利金      每日Theta     年化資金殖利率

=========    =======    ===========   ========================
7天           最低        最高          極高（但不穩定）
14天          低          高            高
30天          中          中高          最佳甜蜜點
45天          較高        中            最佳甜蜜點
60天          較高        較低          普通
90天          最高        最低          偏差

總殖利率 = 國庫券殖利率（現金擔保）+ 賣權權利金殖利率（選擇權）

≈ 4.0%/年 + （權利金 ÷ 履約價）×（365 ÷ 剩餘天數）

防禦操作手冊（機械化版本）：

觸發條件                              對應動作
=================================    ===============================
賣權達最大獲利50%，剩餘天數>7天        買回平倉，重新部署資金
賣權達最大獲利80%                      一律平倉
標的股票跌至履約價，剩餘天數≥14天       持有；讓時間說話
標的跌破履約價5%，剩餘天數7天          決定：接受執行或展期
標的跌破履約價10%，任何剩餘天數         接受執行，除非看法已改變
合約存續期間內有財報公布               一開始就避免這種情況

結果                              稅務處理

============================    ==============================
賣權到期失效                    全額收取的權利金計入短期資本利得
低於成本買回平倉（獲利）          （收取的權利金 - 支付的金額）計入短期資本利得
高於成本買回平倉（虧損）          短期資本損失（可抵消短期/長期資本利得）
賣權被執行→承接股票              權利金降低所承接股票的成本基礎；
股票的持有期間自執行日當天起算

30-delta CSP（标准型）：
30天、sigma=22%的合约约虚值5-7%
被行权概率约30%
三种预设中期权费最高
适合：实际上想积累该股票的投资者


16-delta CSP（一个标准差）：

约虚值9-11%，被行权概率约16%
期权费约为30-delta的一半
适合大多数初学者——你的出价足够低于市场价，

    被行权感觉像是真正捡到了便宜


10-delta CSP（保守型）：

约虚值13-15%，被行权概率约10%
期权费约为30-delta的三分之一
适合：将看跌期权视为纯现金租金、只在出现明显

    回撤时才欢迎被行权的投资者

期限          期权费    日theta    年化现金收益率

=========     =======   =======    =================
7天           最低      最高       很高（但不稳定）
14天          低        高         高
30天          中        中偏高     最佳区间
45天          较高      中         最佳区间
60天          较高      较低       一般
90天          最高      最低       较差

总收益率 = 国债收益率（现金抵押）+ 看跌期权费收益率（期权）

~= 4.0%/年 + （期权费 / 行权价）×（365 / 到期天数）

防守操作手册（机械版）：

触发条件                              操作
==============================        ===============================
看跌期权已达最大利润50%，且>7天到期    买入平仓，再次部署
看跌期权已达最大利润80%              务必平仓
股价在行权价，还剩14天以上           持有；让时间发挥作用
股价跌至行权价以下5%，还剩7天        决定：接受被行权还是展期
股价跌至行权价以下10%，任意到期期限  接受被行权，除非投资逻辑已破坏
合约存续期内有财报发布              事前就应避免此类标的

结果                          税务处理

============================  ==============================
看跌期权到期归零              全额期权费计入短期资本利得
看跌期权盈利买入平仓          （收取 - 支付）计入短期资本利得
看跌期权亏损买入平仓          短期资本损失（可抵消短期/长期资本利得）
看跌期权被行权→获得股票       期权费降低股票的成本基础；
股票持有期从被行权日起算