Airplane wings are a big part of Triumph Group's business. Image source: Getty Images.

What happened?

Shares of airplane parts supplier Triumph Group (NYSE:TGI) gained 13.7% in November, according to data from S&P Global Market Intelligence.

So what?

Those gains didn't come easy, though. In fact, Triumph Group shares sold off early in the month after the company reported weak fiscal Q2 numbers. Q2 2016 earnings of $0.70 per share fell short of Wall Street's expected $0.84 profit, while sales of $874.8 million likewise lagged expectations for $907.8 million in revenue.

All that changed on Nov. 8, however, when Donald Trump won election to the White House, striking a match under the stock prices of aerospace (and other industrials) stocks and sending Triumph Group stock soaring.

TGI Chart

TGI data by YCharts.

Now what?

Triumph told investors last month that it expects to earn between $3.15 and $3.45 per share this year. Considering that last year Triumph lost $21.29 per share, those profits probably sound pretty good, but let's put them in context for you.

Assuming Triumph hits the top of its guidance, $3.45 per share will still be less money than Triumph earned in any of the four years preceding its 2015 loss. Likewise, the $3.5 billion to $3.6 billion in revenues that Triumph expects to book this year will be a worse result than the company has booked since 2012 (in which revenue totaled $3.4 billion).

On the other hand, at a share price of just $28, $3.45 per share in profits this year would give Triumph Group stock a price-to-earnings ratio of just 8.1. In other words, the stock is inexpensive.

Just remember that there's a reason Triumph Group stock is so cheap.