A federal judge is close to a issuing a surprise ruling that would block CVS's (CVS - Get Report) $69 billion acquisition of Aetna, the New York Post reported on Tuesday. 

Citing sources familiar with the proceedings, the Post reported that U.S. District Court Judge Richard Leon warned lawyers at a little-noticed hearing last week that they may want to cancel their summer vacation plans as he contemplates blocking the mega-merger on concerns it could raise prices and kill choices for consumers.

A key issue for Judge Leon is whether the U.S. Department of Justice properly evaluated the potential impact of adding some 21 million Aetna customers to CVS's pharmacy-benefits management business, the Post said.

Oral arguments are scheduled for July 17, with an expected ruling soon after.

.@CVSHealth to open additional #HealthHUB® locations in 2019. Learn more: https://t.co/kKCQ2tBNWA pic.twitter.com/rCuGT3KrW1

— CVS Health (@CVSHealth) June 10, 2019

"I think Leon rules against us," a source working with CVS and Aetna told the Post, speaking on condition of anonymity. "If he rejects the settlement, we would have to figure out the next steps."

Shares of CVS were down 1.5% at $54.17 in trading Tuesday on the New York Stock Exchange. 

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