Carl Icahn has some thoughts about insurer Cigna’s proposed mega-deal with pharmacy benefits manager (PBM) Express Scripts—and he’s not holding back.

In an open letter released Tuesday, the billionaire activist Icahn unleashed a tirade of criticism on the $54 billion Cigna-Express Scripts merger, urging Cigna shareholders to reject the deal and warning that it could be a historically catastrophic corporate marriage.

“Purchasing Express Scripts may well become one of the worst blunders in corporate history, ranking up there with the Time Warner/AOL fiasco and General Electric’s long-running string of value destruction,” wrote Icahn, citing one of the most heavily criticized mergers of the past few decades. Icahn reportedly has acquired a “sizable” stake in Cigna, according to the Wall Street Journal, but the precise extent of that stake is unclear.

Icahn also mentioned the specter of Amazon entering the prescription drug business as a key reason why the Cigna-Express Scripts merger would amount to a “$60 billion folly,” adding that recent federal government actions scrutinizing the largely opaque benefits management industry are also a major red flag. PBMs have been accused of being one of the key reasons why prescription drug prices remain so high.

“When Amazon starts to compete as we believe they will, with their 100 million Prime users and scale distribution system, they will have no trouble breaking into the so called ‘ecosystem.’ With lower prices, the beneficiary will be American consumer, not the owners of Express Scripts,” wrote Icahn in an underlined section of the letter. Icahn also disclosed that he has taken a short position on Express Scripts, expecting the stock to fall.

Cigna and Express Scripts had not released official statements responding to Icahn’s comments as of press time.

Shares of Cigna have risen about 5% since news of Icahn’s opposition to the deal first emerged last week, while Express Scripts stock has fallen about 2%. Shareholders are expected to vote on the deal on Aug. 24.

Read on for the day’s news.

DIGITAL HEALTH

Hepatitis C-infected organs may be safe for transplant. A small, early trial suggests that recent advances in hepatitis C treatment could potentially be a boon to thousands of Americans on the waiting list for organ transplants. University of Pennsylvania researchers said that 20 patients were successfully able to have kidney transplants infected with the virus but were then subsequently cured (or, at least at this point, functionally clear of HCV), with powerful new treatments. (Hepatitis C affects the liver but can spread to other organs, and transplanting organs from these individuals could potentially spread the virus.) With more than 100,000 people on transplant waiting lists—and a major shortage of available organs—the study authors hope these techniques could help cut the backlog.

INDICATIONS

Spark shares plunge on hemophilia trial. Shares of biotech Spark Therapeutics plunged more than 29% in Tuesday trading while rival BioMarin shot up 6.5% as the latter company appeared to notch an advantage in clinical trial results for a gene therapy to treat the rare blood disorder hemophilia A. That's not to say Spark's own treatment didn't work in boosting levels of a critical blood clotting protein, as the therapy's goal. But a pair of patients in the Spark trial also encountered some adverse side effects because of an immune response, likely explaining the stock market beating Spark felt today.

THE BIG PICTURE

Female heart attack patients may benefit from female doctors. One of the reasons health care, and public health, is so complicated is the sheer number of factors affecting it. Environment, education, sociopolitical realities, genetics, and pure chance all play a role in human health. A new study published in Proceedings of the National Academy of Sciences (PNAS) highlights of these factors: The social connection between a patient and her doctor. My colleague Lucas Laursen breaks down some of the implications of the study, which finds that women heart attack patients were far more likely to survive if treated by female doctors: "Concordance might be good for your health because symptoms differ across groups and many doctors may only look for those that apply to them. For example, women can experience different heart attack symptoms from those experienced by men. Another reason might be improved communication and trust between doctor and patients." (Fortune)

REQUIRED READING

How to Fix the 'Urgent Problem' of Black Women's Equal Pay, by Sheryl Sandberg and Laphonza Butler

Speculators, Not Drug Dealers, Dominate Bitcoin Use Now, by Bloomberg

West Virginia Offers Mobile Voting for Troops Abroad This Summer, by Renae Reints

Chinese Media Warns Apple Could Be 'Bargaining Chip' In Trade War, by Don Reisinger