Exchange-traded bond funds enjoyed record quarterly inflows in the first three months of 2017, attracting $44.5 billion, iShares, BlackRock's index-tracking fund group, said on Tuesday.

The tally surpasses the previous record of $42.5 billion set in the first quarter of 2016, according to iShares, which by itself captured $20.3 billion of that money.

Emerging market debt led the rise, with $15.6 billion of inflows, as demand recovered from the U.S. election win of Donald Trump.

A total of $14.4 billion went into investment-grade credit and $3.6 billion into inflation-linked U.S. Treasury bond funds following a spell of positive global economic data.

Despite weathering several shocks since the 2008-2009 financial crisis, the jury is still out on how ETF funds—which trade as shares and aim to replicate the price of a basket of bonds or other assets—will react if a similar crisis hits.

Concern remains about the ability to buy and—probably more important—sell assets like high-yield corporate debt or that issued in emerging markets, which can become highly illiquid in a major selloff.

In the second quarter, investors are expected to favor U.S. over European-focused ETFs.

"We expect the trend towards U.S. investment-grade credit to continue into the second quarter, driven by yield differentials between the regions," said Stephen Cohen, head of fixed-income beta at BlackRock.

Options activity on bond ETFs is also expected to continue to expand, Cohen said. "While more developed in the U.S., we are seeing strengthening demand in Europe."

This article was provided by Reuters.