Apple announced plans on Tuesday to sell up to $12 billion in bonds to pay for share buybacks and dividends, as blue-chip companies test investors’ appetite for debt after two weeks of turbulent markets.

Investors were also paying attention to Apple on Tuesday as some of Wall Street’s top investors — among them Carl C. Icahn and David Einhorn — disclosed they had sold some of their stakes in the company’s stock over the last three months of 2015.

Apple’s debt sale is the second-largest bond offering this year, behind Anheuser-Busch’s $45.8 billion bond issue in January, and more than twice as large as AT&T’s $5.99 billion offering that month, according to Thomson Reuters.

Apple habitually uses the debt markets despite having $215.7 billion in cash on its books, largely because 93 percent of that cash is abroad and would incur taxes if it were returned home.