Sentiment in the stock market is the most bullish in years, while the credit markets are showing signs of stress. Sound familiar? It should. Back in July, the stock market made new highs even as investors sorted through the collapse of two Bear Stearns ( BSC) hedge funds. That shock wave sent risk premiums in junk bonds and loans rising, and KO'd some financing deals for leveraged buyouts -- but didn't touch stocks until later, when a full-blown liquidity crisis emerged. Then shares dropped 10% until the selling eased in mid-August. Now, on the 20th anniversary of Black Monday -- when the Dow Jones Industrial Average fell 508 points, or 22.6% -- investors are back to extreme optimism, with some signs that stocks are overextended. The warning signs of a fourth quarter credit crunch are growing, and the backstops, balance sheet cushions, and rescue artists may be less available this time around. "The market's been Google-ized," says Randy Diamond, trader at Miller Tabak, comparing broad market optimism to the high expectations for strong earnings from Internet search company Google ( GOOG). Google didn't disappoint after the closing bell Thursday, reporting earnings that beat Wall Street's estimates. Other tech companies like Intel ( INTC) and Yahoo! ( YHOO) have also weighed in with better-than-expected earnings this season. The optimism has sent the number of bulls in the stock market up for an eighth straight week, reaching 62%, the most exuberance since December 2004, according to Investors Intelligence. The proportion of investors identifying themselves as bears fell to 19.6%, bringing the spread between bulls and bears over 40 points. These are extreme sentiment levels associated with market tops, according to the service. MarketVane's measure of bullish consensus in the Nasdaq Composite futures is at 83%, an all-time high.