TOKYO, Dec 14 (Reuters) - Japan's Nikkei share average erased earlier modest gains on Thursday to edge down, while telecommunications shares withered on news that online retailer Rakuten is weighing entry into the mobile carrier market.
The Nikkei was down 0.1 percent at the end of morning trading at 22,726.76. The broader Topix was also 0.1 percent lower.
Shares of Rakuten Inc dropped 3.2 percent after it said it was weighing entry into the mobile carrier market, which would set it up to compete with the telecom giants.
The retailer plans to join a government auction for wireless spectrum to be held in January, potentially becoming the country's fourth major wireless carrier, a source briefed on the matter said.
NTT Docomo Inc dropped 1.2 percent, KDDI Corp fell 2 percent and SoftBank Group Corp shed 2.8 percent.
Panasonic Corp shares rose 2.4 percent, after Toyota said on Wednesday that Japan's largest automaker is entering talks with Panasonic to team up on developing and producing batteries to power its electric and hybrid vehicles.
Kyowa Hakko Kirin shares rose 1.6 percent, lifted by a Nikkei report that the drugmaker expects to more than double its operating profit by 2020. That helped the pharmaceutical sector rise 0.4 percent.
The oil and coal subindex gained 1.5 percent, as crude oil futures rose back toward 2015 highs touched earlier this week. (Reporting by Tokyo markets team; Editing by Simon Cameron-Moore)