Sprint pushed SoftBank Group to an 11-fold improvement in profit for its fiscal third quarter, as the Japanese conglomerate unveiled plans for an initial public offering (IPO) that will separate the company’s domestic telecom activities into a separate unit.

The company saw a huge quarter for the period ending in December, largely on the back of results from its U.S. subsidiary, Sprint. SoftBank reported profit of $8.4 billion, while quarterly sales rose 3.9% to $22 billion. The main positive was Sprint’s ability to reverse its deferred tax liabilities of $7.6 billion, thanks to the tax cut that went through in December. Sprint also added 256,000 net postpaid subscribers in the quarter, beating estimates for an increase of 234,000—that is the company’s highest retail net addition of subscribers in nearly three years.

Despite the quarterly gains, the company has struggled with a valuation gap. SoftBank’s market capitalization is less than half of the value of its assets, which the company said are worth at least $180 billion. And there’s no sign that will organically turn around: Operating profit came in at just $2.5 billion, missing estimates.

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Spinning off the mobile unit is expected to raise capital and help improve the overall market cap for the Japanese giant, and it will be an important piece of Softbank CEO Masayoshi Son’s investment goals going forward.

This will bring “greater clarity and thereby better respond to the various needs of investors,” the company said in a statement. During the earnings call, Son himself added, “With the IPO of SoftBank’s Japan operations, the various parts of the company can continue to grow independently. This way I can also spend more time on longer-term global corporate strategy.”

Son has made several investments in recent months, using cash flow from the telecom operations to take stakes in Uber, China’s Didi Chuxing and India’s Flipkart Online Services Pvt. Last year, Son formed the Vision Fund to focus on technology investments, raising $93 billion from backers like Apple; so far, it has invested about $28 billion to date in technology companies.

SoftBank also owns stakes in Chinese e-commerce giant Alibaba and the silicon specialist Arm, and the IPO will be important in raising cash for more investments, including into companies like Wag, which matches dog owners with dog walkers in what Son called the "dog version of Uber."

“I already spend time every day on Vision Fund, whether it’s meeting with or analyzing prospective companies,” said Son in the call. “It’s extremely exciting and I’m having way too much fun. This is more like pleasure, than work. I tend to forget the time.”

He added, “This group strategy is something I had in mind since the very start. I set out to make a conglomeration of No. 1 companies. That’s easy to say, but difficult to do. I can’t think of anyone else who has done it.”