Stock futures were struggling for direction on Wednesday as investors waited for minutes from the Federal Open Market Committee's most recent monetary policy meeting.

Moderna surged 45% and Merck jumped 5.7% after the two companies said a customized vaccine kept patients cancer-free for longer than standard treatments after melanoma skin cancers had been cut out.

SK Hynix rose 4.5% after the South Korean memory-chip maker said its board had approved a plan to repurchase and fully cancel 40 trillion won ($29 billion) worth of shares.

La-Z-Boy slumped 20% after the furniture maker reported weaker-than-expected earnings for its fiscal first quarter, as sales slid 3% from a year ago.

Lowe's slid 2% after the home-improvement retailer said its full-year earnings and revenue would come in at the bottom end of a previously forecast range, which overshadowed a second-quarter earnings beat.

Keysight Technologies climbed 2.6% after the hardware and software manufacturer beat analysts' third-quarter earnings target and issued guidance that topped what Wall Street was looking for.