(Editors Note: Fred Ruffy from Trade Alert, LLC contributed to this article with Henry Schwartz)

VIX April 20 calls were the most active option contract market-wide on Thursday with well over 150K contracts trading, including a block of 83,100 for 60 cents at midday when the market was 50 to 65 cents. VIX crowd confirms the buyer initiated the trade and paid 65 cents for 50K shortly after, with clearing data showing 136,000 contracts of new open interest at the strike. May 47.5 calls, June 50 calls, and July 30 calls saw opening activity as well.

Total open interest in VIX calls increased by 267,000 contracts, or more than 10X the increase in OI in puts on the index (+24K) for the day. Increased activity in calls on the volatility index surfaced as the S&P 500 continued a four-day losing streak. While the broad market has stabilized early Friday, the flow stands out as the largest single-day increases in VIX call open interest this year and suggests a large investor opening a position in VIX upside calls in anticipation of further market losses or higher volatility in the months ahead.