Even for a region where earthquakes are always possible, the Bay Area has rarely woken up to the kind of temblors that on Monday shook up the semiconductor industry.

Communications chipmaker Broadcom made the biggest takeover offer in tech-sector history, with an unsolicited bid to acquire San Diego-based Qualcomm in a deal valued at $130 billion. The Broadcom offer values Qualcomm at $70 a share, or $105 billion, plus the assumption of about $25 billion in debt.

The move comes just days after Broadcom, which already had its co-headquarters in San Jose, said it would move its legal headquarters back to the U.S., to Delaware from Singapore.

The news of Broadcom's offer came as growing competition among other Silicon Valley chipmakers produced an unusual pairing in the valley: Advanced Micro Devices, which announced in August 2016 it's moving its headquarters to Santa Clara from Sunnyvale, said Monday that it is teaming up with its longtime rival, Santa Clara-based Intel, on a new product. An AMD graphics processor unit (GPU) will be integrated into a new chipset from Intel as the two chip giants take aim at a similar graphics offering from Nvidia, yet another Santa Clara-based chipmaker.

Intel said the new chipsets with AMD technology will launch in early 2018.

AMD's deal with Intel is already done, but Broadcom's offer for Qualcomm faces significant hurdles before any such deal could be secured.

Broadcom's offer of $60 a share, plus $10 in Broadcom stock, puts a 13.25 percent premium on Qualcomm's Friday closing price of $61.81 a share, and would need approval from Qualcomm's shareholders.

Broadcom also would need approval from federal regulators. The enormous offer is likely to draw some of the closest scrutiny ever given to a proposed corporate acquisition.

"There will be a ton of hurdles ... ranging from getting Qualcomm to approve it, to getting it through regulatory officials," said Rob Enderle, president of tech research firm the Enderle Group. "It will likely come down to two things: Whether Qualcomm executive management buys into this, and which group the U.S. administration is closest to."

But Hock Tan, Broadcom's chief executive, said in a statement that a deal to acquire Qualcomm would "position the combined company as a global communications leader with an impressive portfolio of technologies and products."

The proposed tie-up would enable employees at both companies to "benefit from substantial opportunities for growth and development as part of a larger company," Tan said.

Broadcom didn't immediately return a request for information about the size of its current employee base in the San Jose area. The company traces it roots to Irvine, where Broadcom was headquartered until San Jose's Avago Technologies acquired it for $37 billion two years ago. Avago took on the Broadcom name, and made Singapore its legal headquarters and San Jose its corporate headquarters.

At the White House last Thursday, President Donald Trump joined Broadcom's Tan to announce the company would move its legal headquarters back to the U.S.

But it will have to overcome concerns from investors and U.S. officials that a combination with Qualcomm could dominate the market for wireless phone chips.

"Both Broadcom and Qualcomm operate heavily in WiFi and Bluetooth (chips)," said analyst Patrick Moorhead, of Moor Insights & Strategy. "Regulators would have intense interest in this. If jurisdictions took an even broader view of networking, the deal could have serious issues and this would be a networking giant."

The AMD and Intel product alliance represents a different shift, Moorhead said. Chip companies are seeing the benefits of working together in situations that, just a few years ago, would have been unimaginable.

"I'm seeing a greater level of 'coopetition' than I have seen for decades from the two companies," Moorhead said. "I think it's significant and shows just how big the competition between Intel and Nvidia really is."

Intel and Nvidia have both made expanding into self-driving car Relevant Products/Services technology one of their major focuses over the last few years, and AMD has found renewed success in the graphics-chip market, which Nvidia has long dominated.