A Wall Street trader spent about $36 million on a bullish bet on options tied to S&P 500 index growth over the next month, Bloomberg writes.

In Wednesday’s transaction, someone bought about 20,000 call options tied to S&P 500 growth that expire Dec. 30 with a strike price of 4,175. As the benchmark index jumped 3.1% to close at 4,080 points, the contract, priced at $20 apiece, ended up at $50.45, representing a potential 152% profit.

A macro hedge fund with net short positions could be behind such a trade, using the deal as a year-end hedge, according to Alan Rozin, head of institutional derivatives at Oppenheimer & Co.

There was also a separate transaction on Wednesday, this time involving the purchase of about 7,000 call options on the S&P 500 maturing at year-end with a strike price of 4,150. At $21.60, each contract nearly tripled in value and ended the session at $60.60.

Meanwhile, the benchmark index itself is up more than 10% these days from its October low thanks in part to optimism that there could be a slowdown in Fed rate hikes.

Amid the rally, a separate investor sold put options on the S&P 500, likely closing out a bearish position, and bought call options. The transaction involved selling 27,000 call options maturing in January with an exercise price of 3,600 and buying about 9,000 call options maturing on Dec. 30 with an exercise price of 4,200. With an initial premium of $27, each call closed at $40.50.

Steve Allred, an equity and fixed-income trader at Cutter & Co. said Wednesday’s rally was largely driven by bears forced to unwind their positions and cut losses.