Specialty vaccine maker PaxVax Inc. has changed owners again, more than doubling its equity value in two and a half years.

The Redwood City, California-based company was acquired by Cerberus Capital Management in December 2015 for $105 million from Ignition Growth Capital and other investors. The sellers retained a minority stake, while Cerberus took the majority.

In August, the company was sold to Emergent BioSolutions Inc. (NYSE: EBS), which develops and commercializes specialty products for use in biodefense and commercial markets. Emergent paid $270 million, 3.4x revenue, based on statements that the target’s 2019 revenues are expected to be between $70 million and $90 million.

PaxVax’ vaccines include treatments for typhoid fever (Vivotif) and cholera (Vaxchora), and the company claims a “robust pipeline” of drug candidates at various stages of preclinical and clinical development for adenovirus, chikungunya, hepatitis A, HIV and Zika.

This is Emergent’s biggest deal yet, by price, anyway, of the 11 acquisitions it’s made public since 2005. The closest in price to this transaction was announced in December 2013, when the company paid $222 million (1.9x revenue) for Cangene Corporation (formerly TSX: CNJ.TO), one of Canada’s oldest biopharmaceutical companies. Cangene’s biodefense, commercial specialty biopharmaceuticals, and contract manufacturing products were highly complementary to EBS’s business.