The private fund sold its 45 million shares, equivalent to a 6 percent stake, for around VND1.3 trillion (US$57.65 million) on March 14, according to business news website cafeF.
It cited an unnamed source as saying that the buyers were foreign companies, including Singapore sovereign fund GIC.
Earlier this month the Hong Kong subsidiary of Switzerland-based financial company Credit Suisse sold its 8.9 million shares in the company to two Vietnamese individual investors for VND660 billion (US$29.27 million), according to the Vietnam Security Depository.
Masan owns 32.53% of the company and another 13.37% through its subsidiary, Sunflower Construction Co., Ltd.
US private equity fund PENM II is another major foreign investor with a 5.36% stake, cafeF reported.