Bitcoin options: heavy calls above $78k, thin cover in low $70ks

Investors bought put protection near $60,000 and loaded call positions above $78,000 ahead of the end‑September Bitcoin options expiry, according to analysis by DWF Labs. End‑of‑September open interest totals 130,670 BTC, compared with 79,003 BTC for August. September and December expiries together account for 59.3% of all Bitcoin options open interest, a pattern consistent with quarterly roll activity.

The top five strikes make up 31% of September’s open interest, similar to concentrations seen in December and March. The largest single call sits at $70,000 with 11,308 contracts; Bitcoin already trades about 9.8% above that strike, indicating many of those contracts are deep in the money. About 27% of September’s open interest is more than 30% away from the current spot price, versus 13% for August, reflecting a substantial share of far‑out option wings.

Upside positioning clusters between $78,000 and $82,000, where roughly 14,000 contracts sit across three lines, and there is a notable concentration at $100,000. Downside put protection is heavier at $60,000 and below. Between roughly $68,000 and $75,000 the options book thins significantly. Martin Lee of DWF Labs warned, “A sharp move down into the low 70s would land in the thinnest part of the book.”

Options skew has changed in recent weeks. Puts were trading richer than calls from December 2025 through August 2026, while end‑September calls now trade about 0.97 volatility points richer than puts, a shift from calls being roughly 4.96 volatility points cheaper on Aug. 3. US‑listed spot Bitcoin ETFs recorded about $1.92 billion of inflows last week. Options trading volumes rose from 14,983 contracts in the week of the July Federal Reserve meeting to about 64,749 contracts around Aug. 19.

The US Treasury raised the maximum size of its long‑end buybacks from $2 billion to at least $4 billion starting Sept. 9. Market commentary linked the buyback plans to easing long‑end yield stress and renewed demand for assets amid a weaker dollar. Bitcoin moved from about $64,100 to near $77,000 during that period, and roughly $4 billion of short positions were cleared.

The September book runs about 1.8‑to‑1 in favor of calls over puts. Analysis of the position composition and strike concentration identifies the low $70,000s as the zone with the least options coverage in the current expiry structure.