Blue-chip companies have sold more than $1 trillion of bonds in 2017, passing that milestone for the sixth straight year, as Federal Reserve rate hikes spur companies to borrow while it's still cheap.

Sales from Amazon.com Inc. and Philip Morris International Inc. helped the corporate bond market reach the $1 trillion mark faster this year than ever before, according to data compiled by Bloomberg. August is traditionally a relatively quiet month, but that hasn't stopped companies from selling large amounts of debt in recent weeks, including a $17.25 billion deal from British American Tobacco Plc.

Borrowing might grow more expensive as the Fed decides how fast to push up interest rates. The rest of the year will likely be more subdued, according to Dan Mead, head of the U.S. investment-grade syndicate desk at Bank of America Corp., who said last week that companies may be pushing to raise cash now before it gets harder.