If CVS buys Aetna, it wouldn't only be the largest U.S. merger of the year -- it would be the largest American health insurance deal of all time.
CVS (CVS) is considering buying Aetna (AET) for about $66 billion, according to the Wall Street Journal. The companies are reportedly in active merger discussions.
The hefty price tag would easily surpass Express Scripts' $29 billion acquisition of Medco in 2012, the current largest health provider merger.
If the two companies agree to the deal, it would also be much larger than the two most expensive deals of the year, according to analytical firm Dealogic. Medical equipment supplier Becton Dickinson announced plans to acquire C R Bard for $24 billion and United Technologies has a $23 billion deal to acquire Rockwell Collins.
Related: Amazon may be factor behind rumored CVS, Aetna merger
Mergers and acquisitions have been on a downward trend from their 2015 peak, according to Datalogic. The total dollar value of corporate deals is down 29% this year -- and half of what it was in 2015.
Tech sector mergers have also fallen this year their lowest point since 2003, Morgan Stanley says.
"The current M&A cycle appears to be ending in the US," the firm wrote in a research note Thursday.
Still, there has been significant activity in the health care space -- even if two of the biggest deals never saw the light of day.
In 2015, Anthem agreed to acquire Cigna for $54 billion and Aetna and Humana announced a $34 billion merger, but both deals fell apart. Federal judges blocked the pair of deals in February, citing antitrust law.
Related: Aetna-Humana & Anthem-Cigna: Two mergers die in one day
M&A might be dying down, but momentous deals are still happening. For example, United Tech's blockbuster partnership with Rockwell would become of the biggest aviation mergers in history.
AT&T's (T) $85 billion megadeal with Time Warner (TWX) -- which includes CNN -- is currently the largest agreement still pending, according to Datalogic. The Justice Department is expected to complete its review of the agreement by the end of the year.
And the largest successful acquisition in U.S. history? Verizon's Communications $130 billion 2013 agreement to buy out Vodafone Group's 45% stake in its wireless business.