Wednesday was a historic day in Washington, with President Trump signing the Republican tax reform package into law. Yet after having seen huge gains in anticipation of its passage, the stock market largely ignored the closing scene of the tax reform saga, and major benchmarks remained very close to where they began the day. Even with the positive tone on the political front, some companies suffered from negative events that hurt their shares. Red Hat (NYSE:RHT), MannKind (NASDAQ:MNKD), and Navistar International (NYSE:NAV) 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.

Red Hat falls despite solid earnings

Shares of Red Hat fell 5% after the company reported third-quarter financial results late Tuesday. On its face, the report looked quite positive, with the open-source technology specialist seeing revenue jump 22% on strength in its cloud computing-related offerings. Adjusted net income also climbed by 20%, with solid gains in subscription-based revenue pointing to the stability of Red Hat's business model, and the company predicted a good end to its fiscal year. With the stock having been up by more than 70% year to date coming into the report, Red Hat's drop likely stems simply from shareholders' desire to lock in a portion of their gains during 2017.

Red Hat logo in front of a staircase going up.

Image source: Red Hat.

MannKind builds downward momentum

MannKind stock fell another 11%, adding to its losses from earlier in the week. On Monday, shares of the biotech company's shares fell by double-digit percentages following discouraging sales figures for its Afrezza inhaled insulin product. Subsequent declines have reflected investor concerns that with Afrezza not bringing in enough sales to finance its current rate of cash spending, MannKind might well have to raise more capital through dilutive stock offerings or other means that could harm current shareholders. Unless the company sees a sales uptick or can find a new partnership to provide it with capital, this week's slump could continue into the future.

Navistar gives back ground

Finally, shares of Navistar International fell nearly 6%, giving back most of their gains from the previous session. On Tuesday, Navistar climbed 7% after reporting extremely strong fiscal fourth-quarter financial results, which included dramatic sales gains and favorable shipment guidance for the coming fiscal year. Yet today, Navistar got a negative review from analysts at Gabelli, who cut their rating on the stock from buy to hold and pointed to commodity inflation, internal cost increases, and slower future growth as reasons to have less confidence in the trucking company's future. Even after today's decline, Navistar is up more than 40% so far in 2017.

Dan Caplinger has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.