The max pain price for Friday's bitcoin options expiry is $44,000.
"Historically, Fed taper has been a headwind for bitcoin," one fund manager said.
"It is normal for investors to reduce exposure to enter at a lower price," one observer said.
The data doesn't necessarily indicate that the traders are betting on price declines.
Bitcoin has taken back half of the gains lost in the April to July period, but bullish momentum may slow.
The dollar may depreciate after Friday's event, triggering renewed inflows into bitcoin and equities.
The token remains below the 2 1/2-month high of $3,188 reached over the weekend.
The ether-bitcoin price ratio has broken out to the upside – possibly an indication of a more buoyant risk-taking mood among crypto traders.
"There was a flurry of call buying and put selling after the London fork," one trading firm said.