Indexes down: Dow 0.05%, S&P 500 0.07%, Nasdaq 0.27%
Trump cancels US envoys' visit to Pakistan
Qualcomm up 2.2% on report of OpenAI tie-up
Microsoft down 1.2% after amended partnership with OpenAI
Updates after market open
By Niket Nishant and Utkarsh Hathi
April 27 (Reuters) - Wall Street's main indexes were marginally lower on Monday, ahead of a torrent of earnings this week, as stalled peace talks between the U.S. and Iran kept investors on edge.
Stocks have climbed to fresh highs in recent days on earnings optimism even as back-and-forth headlines on the U.S.-Iran war swayed sentiment.
The optimism will face a key test during the quarter's busiest stretch of earnings this week. According to Raymond James, companies accounting for roughly 44% of the S&P 500's market capitalization are scheduled to report this week.
Of the 139 companies in the benchmark that reported as of Friday, 81.3% surpassed earnings expectations, compared with the prior four-quarter average of 78.1%, according to data from LSEG.
However, some analysts have questioned how reliable the results are as a guide to future performance, since they reflect only one month of disruption linked to the Middle East war.
"While earnings are now demanding a lot of focus from investors, certainly the constant drumbeat in the background is the Iranian conflict," said Peter Andersen, founder at Andersen Capital Management.
"There doesn't seem to be any progress on a resolution. Once the earnings period is over, investors probably will start to refocus on the Iranian conflict and what it means in the long-term impact for the equity markets."
U.S. President Donald Trump canceled a visit by two U.S. envoys to Pakistan, dealing a new blow to peace prospects.
At 10:10 a.m. ET, the Dow Jones Industrial Average .DJI fell 25.18 points, or 0.05%, to 49,205.53, the S&P 500 .SPX lost 5.16 points, or 0.07%, to 7,159.92 and the Nasdaq Composite .IXIC lost 67.96 points, or 0.27%, to 24,762.66.
The trajectory of oil prices remains the biggest unknown, as the crucial Strait of Hormuz is still closed. Brent crude futures LCOc1 were trading about 2% higher on Monday and are 43% above pre-war levels.
Investors will also hear from Federal Reserve policymakers, who will gather in Washington this week in what may be Jerome Powell's last meeting as head of the U.S. central bank.
Republican Senator Thom Tillis said on Sunday he would allow the Senate confirmation of Fed chair nominee Kevin Warsh to go forward, after the Department of Justice dropped an investigation into Powell that Tillis said was a threat to the central bank's independence.
"With those obstacles now removed, the path appears clearer for Warsh's confirmation ahead of the next policy meeting (in June)," said Jefferies' chief U.S. economist Thomas Simons.
A Reuters poll of economists last week showed that the Fed is expected to wait at least six months before cutting interest rates this year.
Four of the eleven main S&P sectors were in the red, with the S&P 500 consumer discretionary .SPLRCD leading losses with a 0.9% drop.
Qualcomm QCOM.O was up 2.2% after an analyst said OpenAI was working with the chip designer and Taiwan's MediaTek 2454.TW to develop smartphone processors.
Microsoft MSFT.O declined 1.2% after OpenAI said on Monday that the cloud computing provider will not have exclusive access to its artificial intelligence models and products.
Domino's Pizza DPZ.O dropped 10.3% after the pizza chain missed first-quarter sales estimates.
Nvidia NVDA.O gained 0.6% after jumping 4.3% in the previous session. The company has reclaimed a market valuation above $5 trillion.
Advancing issues outnumbered decliners by a 1.45-to-1 ratio on the NYSE and by a 1.23-to-1 ratio on the Nasdaq.
The S&P 500 posted 13 new 52-week highs and five new lows while the Nasdaq Composite recorded 85 new highs and 52 new lows.
(Reporting by Niket Nishant and Utkarsh Hathi in Bengaluru; Editing by Devika Syamnath)
((Niket.Nishant@thomsonreuters.com;))