The mobile phone unit of Japanese tech giant Softbank had a disappointing debut on the Tokyo stock market.
The firm raised as much as 2.6 trillion yen ($23bn; £18bn) by selling shares at 1,500 yen each in one of the world’s largest ever stock offerings.
But by the close of trade in Tokyo, shares were down 14.5% from the price set for its initial public offering.
Analysts said the disappointing debut was not entirely unexpected.
“Softbank wasn’t as popular an [initial public offering] as the market had expected,” Singapore-based market expert David Kuo told the BBC.
“It was oversubscribed, but not as much as hoped.”
Investors may have been wary over a number of developments in Softbank’s business.
There is the prospect of a price war after Japan’s two biggest mobile phone operators said they would cut the cost of calls next year.
The firm’s reputation suffered when its network failed in large parts of Japan two weeks ago.
Also, Softbank may have to replace expensive kit made by Huawei, the controversial Chinese firm, after the Japanese government said Huawei equipment threatened national security.
Originally a telecoms firm, Softbank has become a vast conglomerate covering robotics, chips and investments.
The firm was founded by Japan’s richest man, Masayoshi Son.