Steve Ballmer has surpassed Bill Gates to become the wealthiest former CEO of Microsoft Corp. (NASDAQ:MSFT), riding on the back of the company’s AI-driven stock rally. What Happened: Ballmer’s net worth has now reached $157.2 billion, making him the sixth-richest person globally, according to the Bloomberg Billionaires Index. This marks the first time Ballmer has overtaken Gates, the co-founder of Microsoft. The surge in Microsoft shares, which have seen a 21% increase this year, has significantly contributed to Ballmer’s wealth. Over 90% of his net worth is tied to Microsoft shares. On the ot…