Stats Investment Management Co., whose hedge fund posted a positive return in each of the past 10 years, said the era of easy gains in the Japanese stock market fueled by Abenomics is over.

Equities surged almost 80 percent in the three years through 2015, buoyed by Prime Minister Shinzo Abe's efforts to boost the economy and spur inflation. Those efforts are sputtering, and despite more than three years of the Abenomics program, the economy contracted at a faster pace than expected in the last three months of 2015. The Bank of Japan on Jan. 29 adopted a negative interest rate for the first time in history.

"Abenomics provided a special period where you could make money on almost anything you invested in," said Toru Hashizume, chief investment officer of Tokyo-based Stats. "For those who have invested in the stock market based on a belief that the market contains little risks, they will start to exit as the market becomes volatile. I see this trend continue."