Tuesday was not a good day on Wall Street, as the major market indexes closed with losses of in the neighborhood of 1%. Uncertainties surrounding North Korea continued to dominate investors' attention around the world, especially as comments from leaders in Russia and China showed the complexity of the situation stemming from its recent nuclear tests and escalating rhetoric. But while some may have taken geopolitics or weather-related concerns as reasons to take money off the table, there are also investors who sold to play the odds of history: Over many decades, Septembers have been, on average, among the worst months for the stock market.

Some stocks, of course, suffered Tuesday due to their own company-specific setbacks: Mallinckrodt (NYSE:MNK), Universal Insurance Holdings (NYSE:UVE), and Cellectis (NASDAQ:CLLS) were among the worst performers on the day. Below, we'll look more closely at these stocks to tell you why they did so poorly.

Mallinkrodt deals with a legal setback

Shares of Mallinkrodt fell more than 12% to $36.12 after the pharmaceutical company suffered a painful loss in federal court. The drug maker had been looking to defend its patents related to its respiratory treatment system, Inomax, against potential generic competition. Instead, a Delaware judge ruled that the competing product didn't infringe on any patents that Mallinckrodt had. That setback put further pressure on the shares, which had already lost substantial ground so far in 2017. The ruling could also reduce interest in Mallinckrodt as a potential takeover target, especially if would-be buyers viewed Inomax sales as an integral part of any value proposition for the company.

Historical picture of several people in a horse-drawn carriage with Mallinckrodt logo.

Image source: Mallinckrodt.

Universal Insurance Holdings braces for Hurricane Irma

Universal Insurance Holdings plunged almost 15% to $18.40 as the entire insurance industry absorbed the potential ramifications of a second major hurricane hitting the U.S. within a month's time. Hurricane Irma increased in intensity to a Category 5 storm earlier on Tuesday, and predictions about its track have gradually shifted southward, such that it now seems more likely to threaten the Florida coast. With Universal headquartered in Florida and doing much of its business in the Southeastern U.S., its shares took an even larger hit than the rest of the industry. In the long run, catastrophic events could strengthen its pricing power, but -- as they've done in relation to past hurricanes -- investors are focusing on the short-term hit to profits that the storm would bring to Universal.

Cellectis comes to a stop

Finally, shares of Cellectis dropped more than 20% to $25.66 Tuesday. The biopharmaceutical company got bad news from the U.S. Food and Drug Administration, which placed a clinical hold on Cellectis' phase 1 trials of acute myeloid leukemia and blastic plasmacytoid dendritic cell neoplasm treatment UCART123. News that a patient in the study had died was the primary cause for the FDA's action. Cellectis expects to work closely with the FDA to figure out how to resume study of the treatment in a way that will boost safety and hopefully avoid further adverse events. Until that happens, investors will be nervous about Cellectis' future.

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