Stock futures were steady on Monday, with Wall Street aiming for more record highs, but traders are growing cautious about whether a President Trump and Russia's Vladimir Putin summit will ease the war in Ukraine.

Warren Buffett is telling investors something -- not through what he has said, but through his actions with the balance sheet of his investment conglomerate Berkshire Hathaway ( BRK.A -0.40%) ( BRK.B 0.83%). These actions should be taken as a warning sign with the stock market reaching elevated valuation levels in recent months.

U.S. stocks drifted to a mixed finish as President Donald Trump’s tariffs on dozens of countries had only a muted effect on markets worldwide.