By Lawrence Delevingne

BOSTON (Reuters) -U.S. stocks reversed course on Monday to finish slightly lower, echoing a decline in oil and Treasury prices, as economic worries related to the Delta variant of the coronavirus outweighed optimism about infrastructure spending and corporate earnings.

Stocks initially cheered the announcement on Sunday by U.S. senators of around $1 trillion in proposed infrastructure stimulus. A rebound in corporate profits also bolstered the case for owning stocks, even as markets stand near records and economic growth is expected to slow.

Those factors helped push the S&P 500 index to a near all-time high on Monday morning, but the benchmark basket ultimately retreated to lose 8.1 points, or 0.18%, to 4,387.16

The Dow Jones Industrial Average fell 97.31 points, or 0.28%, to 34,838.16, and the Nasdaq Composite added 8.39 points, or 0.06%, to 14,681.07.

The MSCI world equity index, which tracks shares in 49 countries, gained 0.37%.

"The Delta variant still represents the most immediate threat to the outlook," JPMorgan market strategists wrote in a note on Monday.

But the bank's outlook cited a surprise decline in British and European COVID-19 cases and positive second quarter economic data from the United States and Europe: "Constructive news last week on Delta and growth trims downside risks."

The risks were not lost on other markets, including in energy. Oil prices tumbled about 3% on Monday as weak economic data from China and the U.S., the world's top oil consumers, and higher crude output from OPEC producers stoked fears of weakness in oil demand and oversupply.

Brent settled at $72.89 a barrel, down 3.3% on the day, while U.S. crude fell 3.6% to $71.26 per barrel and .

U.S. manufacturing continued to grow in July, though the pace slowed for the second straight month as spending rotates back to services from goods and shortages of raw materials persist.

Factories around the world are suffering from supply bottlenecks, which sent prices skyrocketing in July, while a new wave of coronavirus infections in Asia demonstrated the fragile nature of the global recovery.

Treasuries Benchmark 10-year notes last rose 18/32 in price to yield 1.1806%, but were still down from 1.239% late on Friday and continuing a multi-month decline.

Negatively interpreting lower Treasury yields, however, could be a mistake, according to Morgan Stanley strategist Guneet Dhingra.

"Investors are fitting a narrative of excessive pessimism to lower yields," Dhingra wrote in a note on Sunday, noting low hospitalizations in Britain from the Delta variant, "suggesting overstated downside risks from COVID-19."