As the Federal Reserve began its historic purchases of corporate bonds exchange-traded funds, almost half of the Fed’s purchases went into BlackRock funds, according to ETFGI, an ETF research and consulting firm.

The Fed is not the first central bank to buy ETFs as part of a stimulus package, but it is buying both ETFs and corporate bonds for the first time in its 107-year history. The Bank of Japan has been buying equity ETFs since 2012 as part of quantitative easing, says Deborah Fuhr, managing partner of ETFGI.