A headwind for the global equity rally is showing signs of reversing, and that could give a further boost to stocks, according to Citigroup Inc.

Investors have sold a net $230 billion in shares this year amid a 20% rise in a gauge of global stocks, strategists including Robert Buckland wrote in a note Wednesday.

That has only happened twice before and when the trend reversed, inflows helped spur another 20% gain over the next year, they said.

“November is on track to be the first month of inflows into emerging and developed market equities funds in two years,” the Citi team wrote. “If they continue, this could add further momentum to the rally.”

The MSCI World Index of developed market shares has risen 20% in 2019 as hopes for monetary stimulus from the world’s central banks outweighed concern over the impact of the U.S.-China trade war.

“A similar decoupling between share prices and fund flows occurred in 2012 and 2016,” the strategists wrote. “In both instances, as outflows turned to inflows, global equities went up another 20% over the next 12 months.”