Japanese e-commerce giant Rakuten Group has returned to the U.S. junk bond market to shore up more cash for its struggling mobile unit and to help repay debt.

Amazon.com’s competitor in Japan is looking to add on another $200 million (¥26.4 billion) to a series of notes that it first sold last year, according to a person familiar with the matter. Rakuten tapped the market in November for $500 million at a whopping 12% yield. The Morgan Stanley-led offering is expected to price later in the week.

The firm’s November transaction also went to funding capital investments for its mobile business and for the repayment of debt. In December, its ratings were cut further into junk by S&P Global Ratings.