"Markets' little more than passing reaction to the Brussels terror attacks and increasing indifference to economic data (other than on a selective post-hoc rationalization basis), and central bank actions and utterances should be a matter for particular concern," Marc Ostwald, market strategist at ADM Investor Services International, said in a note on Wednesday.
U.S. stock index futures were lower as of 9:15 a.m. ET, while Treasury yields were lower and the U.S. dollar index was higher. Oil declined to trade below $41 a barrel.
Read MoreFed Chair Yellen has a mini revolt on her hands
Overnight, Philadelphia Fed President Patrick Harker said in a Reuters report the central bank should consider another interest rate hike as early as next month if the U.S. economy continues to improve as it has of late. While he supported last week's decision by his colleagues to leave policy unchanged, "there is a strong case that we need to continue to raise rates," he said in the article.
The day's schedule is short on first-division data with U.S. new home sales and crude oil inventories among the highlights.
Weekly mortgage application volume decreased 3.3 percent on a seasonally adjusted basis, according to the Mortgage Bankers Association.
Read More Kensho Trade: How to play new home sales report
On the earnings front, General Mills reported adjusted 65 cents earnings per share for the latest quarter, 3 cents above forecast, but revenue came in light of expectations.
PVH Corp, which owns U.S. apparel brands such as Tommy Hilfiger and Calvin Klein, is also due to report on Wednesday.
Read More movers: GIS, NKE, KKD, RHT, AZO, MRK, AZN, CS, NLSN & moreEarly
February is expected to show an improvement in new home sales due to improvements in the labor market amid a low interest rate environment. The crude inventories number could cause some volatility in oil markets, although Brent and WTI appear to have bottomed at $40 per barrel for now.