San Diego medtech giant Illumina Inc. is said to have received a $30 billion takeover offer from global firm Thermo Fisher Scientific.

The all-stock offer doesn’t include a cash deal, StreetInsider.com and Bloomberg reported, citing an unnamed person familiar with the matter.

This isn’t Illumina’s first acquisition attempt made by a multi-national corporation. Back in 2012, Roche Holding AG made a bid of $6.7 billion for Illumina. The company rejected the offer, and Illumina’s market cap has grown to over $26 billion since. Its revenue has doubled since 2011, totaling $2.2 billion last year.

Illumina is the world’s largest maker of DNA sequencing equipment, and Thermo Fisher is one of its very few competitors.

Wells Fargo analyst Tim Evans told Barron’s stock market blogger Ben Levisohn that the speculation regarding the takeover “makes no sense.”

“We think the deal would encounter significant regulatory hurdles given that Illumina holds a near monopoly in high-throughput sequencing, and Thermo Fisher Scientific is the only current competitor with material scale in desktop sequencing,” Evans said.

Illumina and Thermo Fisher Scientific were not available for comment by press time.