ETH 1675 Put OI Spike Was MM Noise, Until a Block Print Confirmed It

The ETH 17-Jul 1675 put (11 days out, strike 4.1% below the $1745.93 spot ref) built OI from 104 to 651 contracts in 24 hours, a 526% jump worth roughly $916k notional. On detection the taker tape looked mixed — buyerAggression near 0.54, the kind of read that usually means a dealer/market-maker is matching size internally rather than a directional bet forming.

Pulling the full 48h aggressor breakdown changes that picture. Of 54 trades and 552 contracts bought against just 6 sold, one single block trade — 500 contracts, $885,310 notional, printed 06:00-07:00 UTC — now dominates the tape. Post-block buyerAggression on the strike sits at 0.99, and net premium flow is +$15,372 buyer-favored.

Zooming out to the full Jul-17 board, puts are building broadly: 1600 (+5,462), 1500 (+3,337) and 1750 (+545) all show similar net put buying, with the whole expiry's OI flow summary reading put_buying dominant (10,665 contracts of put delta vs zero net call delta). The 1675 strike's spike isn't isolated noise — it's one lot in a wider put-side build below spot, confirmed by a single outsized aggressive buyer rather than balanced two-way matching.