Investors trying to explain the resilience of American equities during a global selloff may want to consider the pace that companies are repurchasing shares.

About 79 percent of buyback orders at Goldman Sachs Group Inc.'s corporate trading desk were active Friday, the most this year, according to a note to clients obtained by Bloomberg News. Companies stepped up purchases as the Standard & Poor's 500 Index fell as much as 3 percent from an intraday record reached Wednesday.

The buybacks may have limited losses in American equities after shares in Japan fell the most in two years and stock markets from London to Paris and Frankfurt saw declines of more than 2 percent. The S&P 500 closed yesterday down 0.3 percent, trimming gains to 16 percent in 2013.