This morning, the day after Republican members of Congress unveiled their plan to repeal the Affordable Care Act, including their precise goals for the new legislation that will replace it. President Donald Trump continued with his Twitter communications, posting that he was "working on a new system," and that drug prices are going to "come way down!" CNN Money said that "immediately, shares of drug and biotech companies... fell."

Stocks of larger-capitalization firms appeared to suffer less-dramatic losses than small-cap issues, with shares of Merck & Co., Inc.

(NYSE: MRK) down 0.5 percent, shares of Phizer Inc. (NYSE: PFE) down 0.8 percent, and shares of Amgen Inc. (Nasdaq: AMGN) down 0.9 percent. Yahoo Finance described drug companies as the "biggest losers" of the changes to perception as a result of the newly unveiled plan and Trump tweet.

Drug stocks hardest hit among healthcare

Drug stocks like Endo International plc (Nasdaq: ENDP), Mallinckrodt Public Limited Company (NYSE: MNK), and Valeant Pharmaceuticals International, Inc. (NYSE: VRX), were among those hardest hit, down 6.2, 4.1, and 6.4 percent, respectively. The downdraft has been accompanied by a two-day swoon in the general market; the Dow Jones Industrial Average is off by 19.84 points, or 0.1 percent, and the Nasdaq Composite Index is down by 6.69 points, or 0.1 percent, at 12:45 p.m.

ET.

Snap Inc. (NYSE: SNAP) stock retreated for the second day, with shares trading down 11.74 percent to $21.15, still more than 20 percent above last Wednesday's $17 initial public offering price. Shares had traded more than 70 percent higher, to $29.44, in heavy trade on Friday. Close to 50 million SNAP shares had traded hands at midday, well below the four-day average volume reported by Yahoo Finance of 145.9 million shares.

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The website noted that, overall, Healthcare stocks have not been left behind in the Trump rally, which has seemed to benefit SNAP stock, and that biotech stocks had "been outperforming" until today's tweet by President Trump.

Healthcare reform common among presidential agendas

Yahoo Finance noted that bringing drug prices "under control" was a campaign promise of not only Donald Trump, buy also of Democratic presidential nominee and former Secretary of State Hillary Clinton.

U.S. Senator from Vermont Bernie Sanders, who also ran for the 2016 Democratic nomination, has also been an outspoken advocate of reform to drug pricing, stating that "access to health care is a human right." Among reforms Sanders has advocated include importing prescription drugs from Canada, where the senator's website reports the government pays 40 percent less than the United States "per person per year" for prescription medications.