U.S. mutual funds struggling to get ahead of passive indexes this year had a solution handed to them on a platter: Alibaba Group Holdings Ltd.

Among 215 large-cap growth funds in the U.S., about one-third hold shares of the New York-listed Chinese e-commerce giant, according to regulatory filings compiled by Bloomberg. They’ve returned an average 33% this year, compared with 24% from managers with no stake. 

Among funds with BABA on board, 89% are beating their benchmarks in 2017, versus 52% without it.

The gap exists because Alibaba has surged 113% and isn’t in any of the biggest American equity indexes. The increase of $260 billion in market value would’ve been like adding a second Apple Inc. were Alibaba in the S&P 500. But since it isn’t, owning it has been gravy for mutual funds measured against it. 

“Alibaba has been the shining star,” said Todd Rosenbluth, director of ETFs and mutual funds research at CFRA in New York. “Owning something that’s off the benchmark and doubled is going to be a significant tailwind for performance.”

The spread in returns highlights a rare instance when listing standards observed by the biggest index providers act almost like stock picking mistakes for investors in passive funds. S&P Dow Jones Indices ruled in September 2014 that Alibaba was ineligible for the best known U.S. equity gauges due to its China domicile. The stock is also excluded from benchmarks such as the Russell 1000 Index.

Alibaba’s performance is reminiscent of what Apple did in 2014. That year, failing to own the iPhone maker was one reason why funds trailed benchmark indexes by the most in almost a decade.

What’s unusual this time is that the appreciation is in a non-American company. Investors have to go back to 2007 to find a similar instance when a U.S.-listed foreign stock added more in market value than Alibaba has done this year while not being included in major benchmarks. Back then it was another China behemoth, PetroChina Co.

“A lot of funds may have strict mandate” that doesn’t allow them to invest in Alibaba, said Katie Reichart, associate director of manager research at Morningstar Inc. in Chicago. Still, some of them “have gone against the grain, ridden out of benchmark picks and it’s been working out for them.”

Hedge funds that have more flexibility picking stocks didn’t shy away from scooping up Alibaba shares though. The stock is among the top five in Goldman Sachs Group Inc.’s hedge fund VIP basket of the industry’s most favored companies.

— Check out China Opening Its Banks Is Great, If You Like Bad Debt on ThinkAdvisor.

Copyright 2018 Bloomberg. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.