(REUTERS) -- The Nikkei average ended flat on Monday to halt a four-day winning streak, with early gains capped by market worries over Greece after negotiations with private creditors failed, raising the stakes for a meeting later in the day at which euro zone finance ministers will decide terms for a debt restructuring. 

Olympus Corp, battling to emerge from a $1.7 billion accounting scandal, surged more than 8 percent after the Tokyo Stock Exchange kept it listed, meaning it will be easier to raise capital, though with a special designation for firms needing to urgently improve internal management. 

It topped the main board as the heaviest traded share by turnover after also getting a boost from a report that Sony Corp  is the leading contender among firms jostling for an equity stake in it.   

Among recently battered electronics makers, Sony advanced 4 percent to top the Topix core 30 list, while Toshiba Corp jumped 4.3 percent. 

I think there is a sense that these companies got a late start to the rally in Japanese stocks and were oversold recently, and investors are buying them back now, said Toshiyuki Kanayama, a senior market analyst at Monex Inc. 

The benchmark Nikkei ended at 8,765.90 after rising 3.1 percent last week, while the broader Topix gained 0.2 percent to 756.79.  

The Nikkei is up 3.7 percent so far in January and if current gains continue to the end of the month it will be its best January performance since 1999. 

Trading volume was moderate , with 2.01 billion shares changing hands on the main board, against the six-week high of 2.6 billion shares on Friday.