SoftBank Group's shares were down as much as 8.7% Thursday, despite a record profit in the March quarter, Bloomberg reported.

The Tokyo-based multinational holding company reported Wednesday a record 4.03 trillion yen ($37 billion) profit from its Vision Fund unit from an investment gain on Coupang in the fourth quarter.

The figure, the biggest ever for any Japanese company, caps a difficult year in which the technology company rode shaky stock markets from lows at the start of the pandemic to recent highs.

Vision Fund's biggest win was a $24 billion investment gain from its 40% stake in South Korean e-commerce company Coupang Inc., which listed in March, The Wall Street Journal said.

Softbank reported a net profit of nearly 5 trillion yen ($45.88 billion) in the year ended March, surpassing the $42.5 billion made by Warren Buffett's Berkshire Hathaway in its last business year, CNBC said.

However, in the past three days, Softbank has lost more than 6 trillion yen ($55 billion) in market value, making investors uneasy about whether SoftBank will continue buying back its own stock after completing a 2.5 trillion yen allocation for repurchases.

Vision Fund went from being the source of the biggest loss in SoftBank's history last year to the main driver of earnings. It earned 2.3 trillion yen in the March quarter.

Meanwhile, SoftBank registered gains from food delivery company DoorDash, which went public in December, and the sale of a majority stake in U.S. telecom company Sprint Corp last year.

"Our profit and revenue are both measured in trillions of yen, but just a year ago we had a record loss," Softbank founder Masayoshi Son said at a briefing, according to Bloomberg.

What has really lifted SoftBank's shares has been its buybacks. Starting March 2020, Son announced he would sell assets and repurchase 2.5 trillion yen of his own stock, the report said.