By Anhata Rooprai

Aug 11 (Reuters) - Intel raised $20 billion from an upsized share offering on Tuesday, as it looks to fund the costly build-out of its chip contract manufacturing business by cashing in on a stock surge fueled by its turnaround efforts.

Once a dominant force in the global chip industry, Intel is investing heavily in new facilities and advanced packaging capabilities as it seeks to challenge industry leaders such as TSMC in contract chip manufacturing.

Intel priced the offering at $95 per share, which was a discount of 2.6% from the previous close. The chipmaker said on Monday it aimed to raise $15 billion through the share sale.

Bloomberg first reported the size of the upsized offering.

Intel's shares fell more than 4% on Monday. As of Monday, the stock has nearly tripled so far this year, outperforming rivals AMD and Nvidia and the Philadelphia Semiconductor Index's nearly 75% rise.

Several analysts have said Intel's surging share price has increased the chances of an equity raise to help fund its expansion plans.

"As a capital-intensive business that went a long way to wrecking its own balance sheet and prospects by focusing on financial engineering rather than physical engineering, courtesy of $82 billion of share buybacks in the 2010s, it makes perfect sense for Intel to raise money, especially after a five-fold increase in the stock price since last August," said Russ Mould, investment director at AJ Bell.

The shift toward AI agents has powered demand for central processing units beyond Intel's manufacturing capacity, prompting the chipmaker to raise its capital expenditure forecast for this year from $18 billion to $20 billion in July.

It also committed to high-volume production of chips using its 14A manufacturing process in 2028, after previously warning the technology could be shelved without a major external customer.

Its foundry unit has won Tesla as a 14A customer and optimism for another marquee client grew after U.S. President Donald Trump said Apple would make processors with Intel, though neither company confirmed it.

Last month, Intel announced a €5 billion ($5.77 billion) investment to upgrade and expand chip manufacturing in Ireland, a project that represents more than 25% of its planned 2026 capital spending.

JPMorgan Securities, Goldman Sachs, Morgan Stanley and Citigroup Global Markets are acting as joint book-running managers.

($1 = 0.8666 euros)