(Bloomberg) -- As bad as the Chinese stock market has been for investors this year, a Morgan Stanley fund has been even worse.

The nine-year-old Morgan Stanley China A Share Fund, the first U.S. closed-end fund to invest in mainland stocks, has slumped 13% this year through Sept. 18 on a total return basis, compared with a 6.2% decline in the benchmark it tracks. The underperformance came as investors sold the fund, pushing it to trade at 24% below the value of the assets it holds, the biggest discount among more than 500 closed-end funds on American exchanges, according to data compiled by Bloomberg.

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