There's been a rush for bullish stock bets this week. More than 10 million call options tied to the State Street SPDR S&P 500 ETF Trust traded in a single session earlier this week, the highest one-day sum on record, according to Cboe Global Markets data. It's a sign that many traders were positioning for bigger gains to come.

So far, they've been rewarded. The S&P 500 is up almost 3% and stock futures are pointing to gains after the opening bell.