The deal raises Nestle's stake to about 19 percent from 14.5 percent as of Feb. 26 and its total investment in Aimmune to $273 million.

The companies also extended their two-year strategic pact to develop therapies for food allergies by another two years, Aimmune said on Monday.

"Some investors were worried that Nestle might sell their original equity investment in Aimmune. However, to us, this suggests Nestle views investment in Aimmune as long-term," Wedbush Securities analyst Liana Moussatos said.

In the United States, there is no approved treatment for peanut allergies, a medical condition that is becoming increasingly common and could be fatal.

Analysts see huge opportunity for Aimmune's oral drug, AR101, which could be one of the first to be made available to patients desperate for treatment options.

Combined with the company's $255 million in cash as of Sept. 30, the investment by Nestle finances Aimmune "well beyond" the anticipated approval and launch of the drug in the United States, Chief Executive Officer Jayson Dallas said.

As packaged food sales slow amid changing tastes, Nestle has been trying to become a "nutrition, health and wellness" company, with its unit, Nestle Health Science, playing a pivotal role.

The unit invested $145 million in Aimmune in 2016, followed by $30 million as part of the company's public offering in February 2018.

Aimmune said Nestle Health Science Chief Executive Officer Greg Behar will continue as a director on its board.

Nestle's per share price of $30.27 is slightly below Aimmune's close on Friday at $30.29. The companies expect to close the equity investment by the end of 2018.

Shares of Brisbane, California-based Aimmune were trading up 1 percent at $30.55 in early trading.

(Reporting by Tamara Mathias in Bengaluru; Editing by Arun Koyyur)

By Tamara Mathias