Major market benchmarks extended Friday's gains on Monday, as investors ignored continued trade tensions to instead look forward to the start of a potentially strong corporate earnings season in the weeks ahead.

Nevertheless, several individual stocks failed to keep up. Read on to see why CTI BioPharma (NASDAQ:CTIC), PetMed Express (NASDAQ:PETS), and Pfizer (NYSE:PFE) each slumped today.

Red arrow chart showing declines with stock-market data in the background

Image source: Getty Images.

CTI BioPharma's trial disappointment

Shares of CTI BioPharma sank 13.9% after the clinical-stage biotech company announced that its phase 3 trial (PIX306) to evaluate combining its Pixuvri cancer drug with Biogen's rituximab failed to meet its primary end point. The combination did not achieve an improvement in progression-free survival when compared with combining Eli Lilly's gemcitabine with Rituximab to treat patients with aggressive B-cell non-Hodgkin lymphoma.

"We are disappointed with the outcome of the PIX306 trial and will proceed to conduct a thorough review of clinical data to assess the next steps for the PIXUVRI program," stated CTI BioPharma CEO Adam Craig. "We would like to express our appreciation to the patients, families and investigators who participated in the study."

As fellow Fool.com contributor Brian Feroldi pointed out, CTI BioPharma investors can take some solace knowing the company still looks forward to the results of its ongoing phase 2 trial for pacritinib, a myelofibrosis drug candidate, early next year. In the meantime, it's hard to blame some investors for taking a step back today.

New competition for PetMed Express

PetMed Express stock fell 12.5% following an analyst downgrade. Craig-Hallum analyst Kevin Ellich moved their rating to sell from hold and also reduced his firm's price target on PetMed Express to $32 from $38, representing a nearly 25% discount from its Friday closing price at $42.62 per share.

To justify his relative pessimism, Ellich noted that Chewy.com's Chewy Pharmacy -- which only just launched last week -- is already competitive with PetMed Express from a price standpoint. This could mean market-share losses and margin pressure for the leading online pet pharmacy.

That doesn't mean PetMed Express can't succeed with its new competition. But with shares up nearly 30% since the beginning of May on a strong quarterly report from the company, it's unsurprising that the stock is giving back some of its gains today.

Pfizer is in Trump's crosshairs

Finally, after climbing as much as 1% earlier in the session, shares of Pfizer briefly turned negative then closed roughly flat in the wake of President Trump tweeting that the pharmaceuticals giant, among others, "should be ashamed that they have raised drug prices for no reason."

"They are merely taking advantage of the poor & others unable to defend themselves, while at the same time giving bargain basement prices to other countries in Europe & elsewhere," Trump added. "We will respond!"

Last week, The Wall Street Journal reported (may require subscription) that Pfizer had increased prices on dozens of its products for the second time this year. WSJ added that Pfizer had increased many list prices by around 9.4% this time, and by "double-digit percentages for the year overall."

Pfizer, for its part, responded that it has modified prices for only 10% of the over 400 medicines and vaccines in its portfolio, and even reduced prices in some cases.

Still, that's unlikely to appease those concerned about potential executive action against the broader pharmaceutical industry, so it's hardly surprising to see Pfizer stock pulling back in response.

Steve Symington has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends BIIB. The Motley Fool has a disclosure policy.