Wall St futures edge up with earnings in focus; PayPal jumps

Meanwhile, PayPal Holdings jumped 18.5% in premarket trading after sources said payments company Stripe and private equity firm Advent International have jointly offered to acquire it for $60.50 per share, valuing PayPal at more than $53 billion.

The earnings season is gathering pace at a crucial point for equities. The S&P 500 has climbed more than 10% this year and, as of Tuesday's close, stood less than 1% below its record closing high from early June, leaving the rally vulnerable to any disappointment in corporate results.

BlackRock reported a jump in second-quarter profit on Wednesday, as a stock market rally boosted the value of client assets. Its shares were 1.9% higher premarket in low volumes.

Investors are now awaiting numbers from Morgan Stanley for further clues on the health of financial firms and capital markets activity. Its shares were up 0.6%.