By Natalia Kniazhevich

The New York Stock Exchange.

(Bloomberg) -- The louder the alarm bells are blaring about the stock-market rally getting excessive, the more investors appear to be tuning them out.

In a market that goes from one record to the next every four days, Wall Street seems too busy chasing the upside to worry about risks like a government shutdown and stretched valuations. A sentiment gauge compiled by Barclays Plc has been sitting near a level that indicates exuberance. A similar Bloomberg Intelligence measure is back to a “manic” zone that’s preceded lukewarm returns in the past.

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Acting on sentiment indicators alone — which have on and off suggested risk appetites have gone too far — would have meant missing out on a rally that’s pushed the S&P 500 to 27 records since June. Few are willing to stick out their necks and bet on the rally’s end when optimism over artificial intelligence keeps propelling the stock market to new highs.

“It is tough to fight the tsunami of optimism now as a disciplined investor until some meaningful negative shock emerges,” said Joe Gilbert, portfolio manager at Integrity Asset Management. “Sentiment is elevated but we can stay extended for awhile.”