NEW YORK — A change of heart by a usually downbeat analyst yanked the stock market from its slumber.

Soaring financial shares propelled indexes to their biggest one-day gain in six weeks yesterday after influential banking analyst Meredith Whitney raised her rating on Goldman Sachs Group Inc., which reports earnings today. Whitney also said on CNBC that hard-hit Bank of America Corp. looks inexpensive given the assets on its books.

It was the best performance for the blue chips since June 1 and follows a month of often directionless trading in which investors looked for any fresh sign that the economy was improving, not simply licking its wounds.

Investors latched on to Whitney's comments because she has for years offered one of the more pessimistic — and accurate — assessments of the banking business.