NEW YORK, June 1 (Reuters) - AI giant Anthropic said on Monday it has confidentially filed for a U.S. initial public offering, teeing up a watershed moment for Wall Street's AI frenzy. Tech stocks continue to lead the Nasdaq composite .IXIC and S&P 500 .SPX in a record-breaking market rally, while Elon Musk's SpaceX is set to price its IPO this month and Anthropic rival OpenAI, led by Sam Altman, is waiting on deck.

MARKET REACTION:

U.S. stocks were mixed on Monday afternoon, with the Nasdaq up 0.3%, the S&P 500 up 0.1% and the Dow industrials .DJI off 0.3%. Salesforce CRM.N rose 10% on Monday, following a report that its stake in Anthropic is valued at $5 billion.

COMMENTS:

JAMIE COX MANAGING PARTNER, HARRIS FINANCIAL GROUP, RICHMOND, VIRGINIA: "This is the part of the cycle where Wall Street gets to see what’s really going on with these companies. If the 1990s template holds, we are set to see the entire tech sector get a boost once the earnings picture on AI becomes less opaque."

DAN IVES, GLOBAL HEAD OF TECH RESEARCH, WEDBUSH SECURITIES, NEW YORK:

"This represents a major step for Anthropic to get ahead of OpenAI as Altman & Co. get ready to go through their own confidential filing. This comes at a much-needed time as SpaceX, which filed its S-1 on May 20th, is set to go on its roadshow later this week pointing to the all-out race to get the much-desired liquidity from public markets with SpaceX, Anthropic and OpenAI all looking to go public in 2026.

"We believe this represents an opening of the floodgates for the IPO market, which has been relatively dormant for a few years, with these three major conglomerates set to go public later this year, but this has turned into a race to reach public markets over the coming months. Investors will be eagerly awaiting more details from Anthropic’s S-1 over the coming weeks."