US stocks have closed flat in quiet trade that still had enough might to push Apple to become the world's most valuable company of all time, eclipsing Microsoft's 1999 record.
The Dow Jones Industrial Average was down 3.56 points (0.03 per cent), finishing at 13,271.64.
The S&P 500-stock index lost a bare 0.03 point (0.00 per cent) at 1418.13, while the tech-rich Nasdaq edged down 0.38 point (0.01 per cent) to 3076.21.
The major indices opened in the red and crawled back to the flatline in thin trade in the thick of summer vacation season.
"There was no data of note released today, so rumours ruled as the empire dozed," said Paul Ausick at 24/7 WallSt.com.
Apple smashed the record books, closing 2.6 per cent higher at $US665.15, valuing the company at $US623.52 billion ($A600.03 billion).
That surpassed the previous record of $US619 billion ($A595.68 billion) set by software titan Microsoft in 1999, during the dot-com boom years.
Apple's stock had begun a steady rise on the Nasdaq late last week amid rumours the tech giant is poised to release new versions of iPhone, iPad, and Apple TV devices.
Best Buy shares plunged 10.4 per cent to $US18.16. Best Buy founder and largest shareholder Richard Schulze on Monday said he was "shocked" that the board had rejected his bid to buy the struggling electronics retailer.
The company announced a new chief executive specialised in turnarounds, Hubert Joly, ahead of its quarterly earnings report, to come before the opening bell on Tuesday.
In merger and acquisition news, health insurance giant Aetna will buy Coventry Health Care, a large provider of government-financed health care such as Medicare and Medicaid, in a deal valued at $US7.3 billion ($A7.02 billion).
Aetna shares jumped 5.6 per cent and Coventry soared 20.3 per cent.
Lowe's shares tumbled 5.8 per cent after the do-it-yourself retailer reported quarterly earnings that missed expectations.
The quiet action came after two straight days of gains had left the Dow on Friday at its highest level since the last days of 2007.
US bond prices were nearly unchanged. The 10-year Treasury yield fell to 1.81 per cent from 1.82 per cent Friday, while the 30-year was unchanged at 2.93 per cent. Bond yields move inversely to prices.
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