The proposal from the Trump administration slashes tax rates for businesses and on overseas corporate profits returned to the country. It offered no specifics on how it would be paid for without increasing the deficit.
"A lot to digest on the tax side and to be honest we don’t have a lot of details at this point aside from just a few bullet points from the press conference," said David Lefkowitz, senior equity strategist at UBS Wealth Management Americas in New York.
"This is going to be a bit of an uphill fight to get this plan enacted into law."
The expectation of a corporate tax cut was partly behind the rally in U.S. stocks since the November election of Donald Trump. The market stalled over the last several weeks as the administration has failed to score a major legislative victory, Republican majorities in the House and Senate notwithstanding.
The S&P 500 traded above its record closing high throughout the day, however. Some analysts say even though tax reform would be a major boost to stocks, economic and earnings growth are enough to support current market levels.
Overall profits of S&P 500 companies are estimated to have risen 11.8 percent in the first quarter, the most since 2011, according to Thomson Reuters I/B/E/S.
The Dow Jones Industrial Average fell 21.03 points, or 0.1 percent, to 20,975.09, the S&P 500 lost 1.16 points, or 0.05 percent, to 2,387.45 and the Nasdaq Composite dropped 0.27 point to 6,025.23.
Despite the tick lower, advancing issues outnumbered declining ones on the NYSE by a 1.37-to-1 ratio; on Nasdaq, a 1.62-to-1 ratio favored advancers.
The tax proposal includes a cut on so-called pass-through business taxes that would deliver a windfall to investors in MLPs, master limited partnerships.
Among stocks, United Technologies
"Earnings are very strong, you could see a 15 percent year-on-year growth on the S&P," said Paul Zemsky, chief investment officer, Multi-Asset Strategies and Solutions at Voya Investment Management in New York.
"We're seeing a global, synchronized up swing."
On the flip side, Boeing
The S&P 500 posted 82 new 52-week highs and 3 new lows; the Nasdaq Composite recorded 210 new highs and 28 new lows.
About 7.33 billion shares changed hands in U.S. exchanges, compared with the 6.44 billion daily average over the last 20 sessions.- Reuetrs