BTC Dec26 70000 Put: $635k Buyer Block Hits Tape, OI Barely Budges

A two-block print on the Dec 25 2026 70000 put (BTC-25DEC26-70000-P) drove buyerAggression to 1.00 in the 17:00-18:00 UTC hour, worth $634,747 of the day's $633,304 net buyer premium on that strike — essentially the whole day's flow landed in one window. That's the z=14.7 spike flagging this as rare size.

What OI delta alone would suggest is a fresh large directional put bet. It isn't quite that clean: the strike's 24h put OI only grew 22 contracts against ~200 contracts of aggressive buying, meaning most of the buying was absorbed without matching OI build — consistent with closing/offsetting flow rather than a new net-short-vol position from the writer side.

Contrast with neighboring strikes on the same expiry:

Strike	Put OI Δ24h	Net Premium 24h	Buyer Aggression	Block Trades
70000	+22	+$633,304	1.00	2
75000	+100	+$1,207,312	1.00	3
78000	+552	-$3,105,054	0.01	3
60000	-52	+$94,506	0.95	2

78000 shows the opposite pattern — heavy OI build on a seller-dominated tape, i.e. puts written to open. The 70000 block is buyer-aggressive size without the matching OI footprint.