Most of the multi-bagger flashback articles we've published are on AI-cycle tickers — semis, infrastructure, mega-cap tech. The MRK 110C 12/8 print is a reminder that institutional convexity also lives in the boring names. Specifically: a four-month bull-call spread on Merck that was in the money before earnings broke and printed 540% at peak.
On December 8, 2025, with MRK trading at $98.93 (depressed by patent-cliff narratives around the 2028 Keytruda exclusivity expiration), an institution bought a 110/120 bull call spread expiring April 17, 2026:
- BUY 110C 4/17: ~30,000 contracts at $2.39 → $7.2M debit
- SELL 120C 4/17: ~14,500 contracts at $0.82 → $1.2M credit
Net debit: ~$6.0M. Defined max width: $10 × 30,000 contracts = $30M paper max if MRK closes above $120 by expiration.
By April 17, 2026 expiration, MRK was at $111 — clearly above the long strike, just below the short strike. The long leg expired with $1.00 of intrinsic; it had peaked at $15.30 (+540%) in late March. Combined trade P&L: +$18.7 million realized on a ~$6M net stake.
First published: Daily Institutional Flow Digest, December 8, 2025 · MRK flow on 2025-12-08.
The two legs
| Field | 110C BUY | 120C SELL |
|---|---|---|
| Date | 2025-12-08 | 2025-12-08 |
| Side | BUY | SELL |
| Strike | 110 | 120 |
| Expiration | 2026-04-17 | 2026-04-17 |
| Volume | ~30,000 contracts | ~14,500 contracts |
| Premium | $7.2M paid | $1.2M collected |
| Entry option price | $2.39 | $0.82 |
| MRK spot at trade | $98.93 | $98.93 |
| Position confidence | VERY_HIGH | VERY_HIGH |
| Outcome | expired ($8.20) | expired ($0.02) |
| P&L per leg | +$17.5M | +$1.2M |
Both legs were OTM at entry (110 strike with stock at $99 = 11% OTM long; 120 strike = 21% OTM short). The structure pays max profit if MRK closes between $110 and $120 at expiration; it pays nearly all of that if MRK gets to $115+ and stays there.
What MRK did
| Date | MRK close | Move from 12/8 |
|---|---|---|
| 2025-12-08 (entry) | $98.93 | — |
| 2026-01-15 | $103 | +4% |
| 2026-02-03 (Q4 earnings) | $108 | +9% |
| 2026-03-15 | $120 | +21% |
| 2026-03-25 (peak) | $125.14 | +26.5% |
| 2026-04-17 (expiration) | ~$111 | +12% |
| 2026-04-29 (today) | $110.95 | +12.2% |
MRK rallied steadily across the four-month window, peaking at +26.5% on March 25 (just shy of the short-strike cap) before drifting back to $111 by expiration. The pattern was two-step: Q4 earnings on February 3 lifted the stock from $103 to $115 over two weeks, then the broader healthcare cohort got pulled up in the early-March risk-on rotation.
What the option did
| Date | 110C 4/17 close | Move from entry |
|---|---|---|
| 2025-12-08 (entry) | $2.39 | — |
| 2026-02-03 (post-earnings) | $7.50 | +214% |
| 2026-03-25 (peak) | $15.30 | +540% |
| 2026-04-17 (expiration) | $1.00 (intrinsic) | -58% |
The peak vs realized gap is the main lesson here. The institution that bought the 110C/120C spread did keep the realized $17.5M because they were defined-risk and held to expiration — they didn't need to time the exit perfectly. A retail trader who bought the 110C standalone at $2.39 and held to expiration got back $1.00 — a 58% loss after a +540% paper peak.
The defined-structure trade is a structurally better expression of the same thesis.
Why MRK rallied
The catalyst chain:
- December 8, 2025 (entry): MRK at $99, sentiment dominated by Keytruda patent-cliff narrative.
- February 3, 2026 (Q4 earnings): Keytruda Q4 sales $8.37B (+7% YoY) — exceeded sell-side estimates. MRK reaffirmed pipeline depth (8 late-stage oncology programs) and capital return guidance.
- Mid-February: oncology conference data on next-gen Keytruda + companion therapies.
- Late March: broader pharma rotation as macro vol spiked (Iran war + CPI shock); defensive names re-rated.
- April 17 (expiration): trade settled cleanly with MRK above the long strike.
The institution sized in 8 weeks before Q4 earnings, captured the post-earnings re-rate, and let the structure expire in the money. That's a textbook multi-week institutional bull spread — defined risk, sized to the catalyst, held through.
Why this trade is a "patient defined-risk structure" example
Compare with TSLA 11/21 long call — that was 90 DTE, single-leg, OTM, sized for explosive convexity. The MRK 110/120 is the opposite: shorter convex window (135 DTE), defined-risk vertical, sized to a thesis where mean upside (12–22% stock move) maxes the payoff and the institution doesn't need a 50% rally to win.
The 110/120 spread cost $6M net. Max paper at the 120 cap was ~$30M (5x). Realized: $18.7M (3.1x). That's the attractive risk-adjusted shape — limited downside, capped upside, and the cap got close to fully filled.
When you see institutional vertical spreads on defensive names with multi-month DTE, the smart money usually isn't predicting a binary outcome — they're sizing to a gradient where the catalyst is broad and the timing is fuzzy.
What this trade did NOT mean
The institution did not have non-public Merck information. They had a thesis (Keytruda Q4 strength + patent-cliff narrative overdone) sized to a defined-risk April vertical. Most UOA prints don't print like this — read the methodology piece for the honest aggregate stats.
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