(Bloomberg) -- ETFs that target value stocks are raking in cash. But the people buying those portfolios should buckle their seatbelts, because there could be some turbulence ahead.

Investors have poured more money into smart beta value funds than any other category for at least 11 straight weeks, data compiled by Bloomberg show. In last week’s holiday-shortened four trading sessions, value ETFs, which track stocks priced at discounts to things like earnings or assets, absorbed $1.1 billion, nearly triple the prior week.

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