Apple (AAPL) stole the headlines on Thursday when it became the first U.S.-listed company to be valued at more than $1 trillion.

“But investors should focus on a different $1 trillion number that will have a key influence on the market: total buyback authorizations likely to be announced this year,” Goldman Sachs’s David Kostin said in a new note to clients.

Public companies will repurchase shares (or pay out dividends) with excess cash when they feel investing for growth and financing M&A don’t offer attractive returns for the risk. It’s a controversial and often politicized use of cash since it’s considered a less productive option that enriches shareholders. But that hasn’t stopped companies, including Warren Buffett’s Berkshire Hathaway (BRK-A, BRK-B), from embracing the activity.

Furthermore, repurchases help boost the stock market.

“Corporate repurchases remain the largest source of demand for shares,” Kostin said. “Since 2000, there has been roughly 85% follow-through from authorization to execution.”

At least some of this can be explained by multi-national corporations repatriating overseas earnings following the enactment of the Trump administration’s tax reform act enacted in December. Indeed, the 2004 repatriation tax holiday…