(Bloomberg) -- Low-volatility ETFs amassed billions of inflows in the first half of the year, as major political risks like the U.K. referendum and the U.S. election scared some investors off higher-yielding investments.

But in the latest sign that they've fallen out of favor, the iShares Edge MSCI Min Vol EAFE ETF saw record one-day outflows of more than $300 million on Wednesday.

"Brexit killed low-volatility — that was the catalyst," according to Eric Balchunas, ETF analyst at Bloomberg Intelligence. "People just breathed a sigh of relief after that point."

Effectively with the U.K.'s referendum (which prompted wild market gyrations that quickly settled) investors had peered into the abyss — and found it wasn't that bad. During what the analyst calls the "sweet spot" when the Brexit vote was over, on the one hand, but U.S. economic data wasn't so robust as to stoke serious bets on higher interest rates, investors' renewed confidence helped derail a streak of outperformance that had gained momentum ahead of the June vote.

The iShares Edge MSCI Min Vol USA ETF (USMV), the largest of its kind, has averaged $25 million in outflows over the past 50 trading sessions, punctuated by withdrawals of more than $500 million on Oct. 5. The Powershares S&P 500 Low Volatility Portfolio ETF (SPLV) has also seen a relatively steady drip of outflows since the start of the fourth quarter.

While their design and names helped them attract investors with a relatively low risk tolerance, their besting of the S&P 500 in the first half of 2016 also fostered performance-chasing, hot money flows.

Since then, these low volatility ETFs have run in two key problems — namely, they haven't always been living up to their names, and their stretch of outperformance has ended.

"Something got lost in translation. People, I think, started viewing it as 'all the upside of equities with limited downside' — they got the opposite — time to sell," writes Brean Capital Head of Macro Strategy Peter Tchir. "This product attracted extremely risk adverse investors — when risk popped up here 'unexpectedly' (I think completely predictably) the holders now sell as they didn't want risk in the first place."

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