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S&P 500 companies have returned a record $1 trillion to shareholders over the past year, helped by a recent surge in dividends and stock buybacks following sweeping corporate tax cuts introduced by Republicans, according to a report.

In the 12 months through March, S&P 500 companies paid out $428 billion in dividends and bought up $573 billion of their own shares, according to Howard Silverblatt, an S&P Dow Jones Indices analyst.

That compares with combined dividends and buybacks worth $939 billion during the year through March 2017, Silverblatt said in a research note.

Earnings per share of S&P 500 companies surged 26% in the March quarter, boosted by the Tax Cuts and Jobs Act passed by Republican lawmakers in December.

Companies have been returning much of that profit windfall to shareholders via share buybacks and increased dividends at never- seen-before amounts, highlighted by Apple's record $23.5 billion worth of shares repurchased in the first quarter.

S&P 500 companies have also plowed some of the windfall from lower taxes into investments toward growth or becoming more efficient. First-quarter capital expenditures totaled at least $159 billion, up more than 21% from the year before, according to S&P Dow Jones Indices.

The biggest overhaul of the U.S. tax code in more than 30 years cut the corporate income tax rate to 21% from 35%.