The balance of shares sold short turned higher last week, snapping a five-week back-to-back decline.
The outstanding balance of short-sold shares stood at 900.17 billion yen at the end of the week, up 28.09 billion yen from a week earlier, according to industry figures.
Having hit a 13-year high of 1.34 trillion yen on March 8, the short selling balance had been falling before turning higher the previous week.
Tightened controls on sales of borrowed shares triggered a flurry of activity to cover short positions last month.
Brokerage officials have cited the strong rebound in share prices as a major factor behind the upturn in short selling.
Tokyo stock prices moved steadily higher along a broad front through much of the week, lifting the benchmark 225-issue Nikkei average back above the 11,500 level for the first time in a month.
High-priced activity enticed investors to sell shares short, counting on a reactionary fall in share prices.
Equities that evidenced conspicuously high balances of short margin positions included Nissan Motor, Seiyu, Mitsui Engineering and Shipbuilding, and Isuzu Motors.
The balance of shares bought on credit meanwhile fell for the first time in six weeks. The long margin position balance stood at 1.24 trillion yen, down 45.18 billion yen.
Many individual investors unwound their long margin positions to cash in on profits.
As a result, the long-short ratio stood at 1.37, down from 1.46 a week earlier. The ratio -- a key indicator of investor sentiment -- hit an all-time low of 0.73 on March 8.