The fund, which has been investing in Vietnam for nine years, lost 7.9 percent in June as the market declined by 7.4 percent.
Among its holdings, the biggest declines were in the shares of real estate developer Nam Long Investment Corp (25 percent), private lender TPBank (16.1 percent) and military-owned bank MB (12.8 percent).
The only significant gainer was stationary producer Thien Long Group (up 15.8 percent).
Investors became cautious after central banks around the world tightened policy to stamp out inflation, PYN said in a statement.
Its biggest holdings as of the end of last month were real estate giant Vinhomes (18 percent), state-owned lender VietinBank (16.9 percent), and the Vietnam Engine and Agricultural Machinery Corp (9.9 percent).
The VN-Index has fallen by over 20 percent this year.