Cautious on Wall Street

LONDON (CNNMoney.com) -- U.S. stock futures indicated a weak open Wednesday as record high oil prices weighed on investors and a cloud of uncertainty was cast over Japan.

At 4:46 a.m. ET, Nasdaq and S&P futures were lower, with a comparison to fair value pointing to a flat to negative opening for Wall Street.

Crude prices kept pushing higher on Wednesday after closing at a record $78.23 a barrel in New York the previous session.

The rise in oil prices comes ahead of the government's weekly report on fuel inventories, due at 10:30 a.m. ET.

The resignation of Japanese Prime Minister Shinzo Abe also added to investor woes, as his exit is expected to unsettle Japanese markets for some time.

The benchmark Nikkei 225 index slid 0.5 percent in the wake of Abe's resignation. Elsewhere in Asia, markets finished mixed. Major markets in Europe also were mixed in early trading.

In major corporate news, chipmaker Texas Instruments (Charts, Fortune 500) slightly raised its third-quarter forecast late Tuesday. The company said it expects earnings of 49 cents to 53 cents per share, versus an earlier forecast range of 46 cents to 52 cents a share.