BIIB Options Chain Analysis

Delayed CBOE data, snapshot 2026-08-18. Spot $209.15.

Put/Call (OI)

0.85

20k P / 24k C

Put/Call (Volume)

0.28

115 P / 413 C today

30d ATM IV

34%

annualized implied move

Call wall

$210

3k contracts

Put wall

$150

2k contracts

Tail hedging

2.5×

deep-OTM puts vs calls

What the positioning says

●Call wall at $210 (3k contracts), 0% above spot — the upside strike the crowd is already parked on; often acts as near-term resistance.
●Put wall at $150 (2k contracts), 28% below spot — the hedge floor; often acts as support.
●Deep-OTM put open interest is 2.5× deep-OTM call OI — an institutional hedging ladder sits under this stock.

Open interest by strike

All expiries combined. Amber lines mark the call and put walls; the dashed line is spot.

IV term structure

At-the-money implied volatility per expiry.

Volatility smile

IV by strike — expiry 2026-09-18. A steep left side = expensive downside protection.

30-day implied volatility history

Daily ATM IV (~30 DTE bucket) collected since March 2026. Rising IV into an event = the market bracing; collapsing IV after = the crush.

Open interest by expiry

Expiry	Call OI	Put OI	P/C	Volume today
2026-08-21	2k	1k	0.59	209
2026-08-28	319	106	0.33	26
2026-09-04	80	69	0.86	1
2026-09-11	70	43	0.61	58
2026-09-18	6k	5k	0.99	81
2026-09-25	108	3	0.03	13
2026-10-02	0	0	—	0
2026-10-16	2k	786	0.51	11
2026-12-18	4k	4k	0.91	42
2027-01-15	6k	6k	1.16	87
2027-03-19	662	522	0.79	0
2027-06-17	854	569	0.67	0
2028-01-21	3k	1k	0.45	0

Source: CBOE delayed quotes, refreshed daily after US market close. Open interest is exchange-reported and lags one session. Research, not investment advice.