By David Bailey and Kevin Krolicki DETROIT (Reuters) - General Motors Corp and Ford Motor Co both ruled out on Friday seeking bankruptcy protection at a time when slow auto sales and the credit crunch have rattled investors and sent their shares plunging. GM shares have fallen near a 60-year low, and Ford shares to a 26-year low on fears the global financial crisis could derail turnaround plans at the two biggest U.S.-based automakers. Ford Chief Executive Alan Mulally told Reuters a bankruptcy filing 'makes no sense' for the No. 2 U.S. automaker and GM said in a statement it was not an option the No. 1 U.S. automaker was considering. GM's statement came a day after its shares plunged by 31 percent, a deeper one-day decline than GM shares saw after the September 11, 2001, attacks or during the 1987 market crash. Ford, which also saw its shares plummet on Thursday, announced that the chief financial officer who was the architect of a crucial 2006 borrowing program would retire, to be replaced by an executive credited with leading the turnaround of the company's European operations. GM said its faced 'unprecedented challenges related to uncertainty in the financial markets globally and weakening economic fundamentals in many key markets. 'But bankruptcy protection is not an option GM is considering,' the statement said. 'Bankruptcy would not be in the interests of our employees, stockholders, suppliers or customers.' GM shares fell as low as $4 early on Friday, the lowest price for the stock since 1949, but recovered after the statement and ended up 13 cents, or 2.7 percent higher, at $4.89 on the New York Stock Exchange.