U.S. stock futures suggested a lower market open on Thursday after the Securities and Exchange Commission subpoenaed General Motors Corp., the world's largest automaker, as part of an investigation into GM's accounting.News that the SEC is probing GM, a Dow component, was pulling down Dow futures. Credit default swaps, representing the cost of insuring against a default by the automaker, rose in Europe. Asian markets were rattled by rumors that the company could file for Chapter 11 bankruptcy, a move which GM strongly denied. "The story of the morning is GM," said Angus Campbell, head of sales and marketing at Finspreads in London. "Their stock is trading a lot lower in Europe, indicating that they will decline by about a dollar when they open up and that has affected the futures. This news could eradicate any good coming out of the corporations reporting today." S&P 500 futures were down 3.5 points, below their fair value, a mathematical formula that evaluates their pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures were down 33 points, while Nasdaq 100 futures lost 6 points. GM shares declined 68 cents to $28.49 on the Inet electronic brokerage system in very light trading. U.S. earnings due before the market opens include Hilton Hotels and blue-chip Exxon Mobil Corp.. Verizon Communications, the largest U.S. telecommunications company, reported third-quarter earnings before items that beat analysts' forecasts by 2 cents. No. 1 U.S. chemical maker Dow Chemical Co. reported third-quarter earnings that beat Wall Street estimates. Shares of Dow climbed 65 cents to $45.50 on the Inet electronic brokerage system. After the close, all eyes will be on software company Microsoft Corp. when it reports first-quarter figures. A rise in oil prices may add to inflation concerns. U.S. crude futures for December delivery were trading 59 cents higher at $61.25 barrel on worries over rising heating oil demand ahead of winter. Investors will get some indications about the health of the economy at 8:30 a.m. when the government reports weekly jobless claims and September durable goods figures.