One of BlackRock's fastest-growing businesses brought in record new cash last month

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BlackRock CEO Larry Fink.

• BlackRock pulled in record money for its exchange-traded-funds platform two months in a row, with $44 billion in December.
• The world's largest asset manager captured about a third of all the money that went to ETFs last year.
• BlackRock's iShares business, already the world's biggest ETF provider, is a major growth area for the firm.

BlackRock set records two months in a row for its dominant exchange-traded-funds business, iShares.

The world's largest asset manager notched its a record first in November, bringing in more than $29 billion, before eclipsing that figure a month later with $44 billion, BlackRock said Tuesday.

In late December, iShares' US head Martin Small told Business Insider that the markets were operating "in stark contrast" to those in 2017, "where everything around the world was going up."

"What is obvious about this year is that investors are embracing the versatility of ETFs to take tactical exposures, hedge risk and build resilient long-term portfolios," he said. "It's clear that the growth of ETFs is not dependent simply on rising markets."

Overall, BlackRock captured about one-third of the $515 billion in money globally that went to ETF strategies last year.

See more: BlackRock is launching a new suite of products to capture a red hot market for do-good funds that could grow to $400 billion by 2028

In October, BlackRock chief executive officer Larry Fink said the $4.7 trillion ETF market could jump to $12 trillion in the next five years.

iShares, already the world's biggest ETF provider, is a major growth area for BlackRock, as individual investors turn to cheaper, and often better-performing, passively managed investments over active strategies. The platform managed $1.9 trillion as of September 30, which represents 29% of the firm's total assets under management.