The money that SoftBank Group Corp. stands to reap from selling Arm Ltd. has climbed by more than $10 billion since the deal was forged last year, giving the Japanese company extra motivation to press ahead with the transaction despite growing regulatory opposition.

When Nvidia Corp. first agreed to buy Arm from SoftBank last September for about $40 billion (¥4.36 trillion), the deal already promised to set a record as the biggest chip industry takeover. An increase in the value of Nvidia stock — the main component of the sale price — has since sent the potential payday for SoftBank above $50 billion.

That’s the good news. The bad news is SoftBank is facing longer odds that it can actually complete the deal. It has to get the transaction past regulators in the United Kingdom, where Arm is based, as well as the European Union, the U.S. and China. It may be difficult to satisfy everyone, which could force SoftBank to pursue a Plan B: an initial public offering of Arm that wouldn’t be as lucrative.