* 10-year Treasury yield hits 3 pct
* S&P 500 and Dow post biggest declines since April 6
* Caterpillar, Alphabet, 3M pull indexes down
* Dow down 1.74 pct, S&P 500 down 1.34 pct, Nasdaq down 1.7 pct (Recasts lead; adds details on Caterpillar)
By Stephen Culp
NEW YORK, April 24 (Reuters) - Wall Street dropped sharply on Tuesday as warnings by bellwether companies of higher costs reverberated as the benchmark U.S. 10-year Treasury yield pierced the 3 percent level for the first time in four years.
Caterpillar, an industrial heavyweight, tumbled 6.20 percent after management said first-quarter earnings would be the "high water mark" for the year and warned of increasing steel prices, although the company beat earnings estimates due to strong global demand.
The S&P 500 and the Dow fell the most in two-and-a-half weeks, and the Dow Jones Industrial Average was down for a fifth day in a row. The S&P 500 is down 1.5 percent year-to-date.
Other companies, including Lockheed and 3M, also gave disappointing updates, adding to the sting of rising Treasury yields. The 10-year yield, a benchmark for global borrowing costs, has been driven steadily higher by a combination of concerns over inflation, growing debt supply and rising Federal Reserve borrowing costs.
"It makes borrowing costs more expensive for corporations. This market rally for the last nine years has been driven by low interest rates, accommodating monetary policy and excess liquidity," said Oliver Pursche, chief market strategist for Bruderman Asset Management in New York.
Higher bond yields could also prompt portfolio managers to weigh moving money into more attractive fixed-income securities at the expense of equities. The stock market had already been spooked by a climb in bond yields earlier in the year, sliding sharply in February..
Diversified industrial manufacturer 3M Co was the biggest drag on the Dow Jones Industrial Average. Shares fell 6.83 percent after the company posted in-line profits as lower taxes offset a miss in operating profits and the company lowered its 2018 earnings forecast.
"We're seeing some of the earnings numbers have come out, and after further review, (investors) realized where all this revenue was coming from," said Paul Nolte, portfolio manager at Kingsview Asset Management in Chicago. "They didn't see it as recurring or indicative of the core business.
"I think what investors had hoped the benefit from taxes would get redeployed back into the company. That's not happening," Nolte said.
The Dow Jones Industrial Average fell 424.56 points, or 1.74 percent, to 24,024.13, the S&P 500 lost 35.73 points, or 1.34 percent, to 2,634.56 and the Nasdaq Composite dropped 121.25 points, or 1.7 percent, to 7,007.35.
Technology stocks also weighed on the major indexes. Facebook Inc fell 3.7 percent.
Alphabet shares fell 4.77 percent, erasing the stock's year-to-date gains as rising expenses and shrinking margins overshadowed the company's better-than-expected quarterly profit.
Apple Inc shares lost 1.39 percent as worries over softening demand for high-end smartphones were underscored as Corning Inc reported a drop in screen glass sales for the first time in at least four quarters.
Fellow technology stocks Amazon.com Inc and Netflix Inc also weighed on the Nasdaq.
"They're kind of pulling each other down," said Nolte. "Investors are saying, 'You know, the group has had a tremendous run over the last two to three years, maybe we should take some money off the table here.'"
Shares of Lockheed Martin Corp, the Pentagon's largest weapons supplier, dropped 6.17 percent. The company reported better-than-expected first-quarter earnings and boosted its full-year sales and profit forecast but did not raise its 2018 cash-flow projections.
So far, 24 percent of S&P 500 companies have reported first-quarter results, with 77.1 percent coming in above the Street consensus, versus the 64 percent average since 1994. Analysts estimate 21.1 percent growth in earnings for the quarter, according to Thomson Reuters data.
On the economic front, U.S. consumer confidence rebounded in April, according to the Conference Board, as short-term optimism improved and the share of consumers expecting their incomes to decline in the coming months hit its lowest level since December 2000.
Oil rose above $75 a barrel to its highest level since November 2014, but then reversed course as U.S. President Donald Trump and French President Emmanuel Macron pledged to try to resolve U.S.-European differences on Iran, easing concerns that the United States might reinstate sanctions against Iran.
Declining issues outnumbered advancing ones on the NYSE by a 1.94-to-1 ratio; on Nasdaq, a 1.71-to-1 ratio favored decliners.
The S&P 500 posted 13 new 52-week highs and 21 new lows; the Nasdaq Composite recorded 61 new highs and 90 new lows.
Volume on U.S. exchanges was 7.22 billion shares, compared to the 6.80 billion average for the full session over the last 20 trading days. (Reporting by Stephen Culp; editing by Leslie Adler)