Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Leidos Holdings, Inc. (NYSE:LDOS) -- or formerly Science Applications International -- fell more than 17% during Tuesday's intraday trading after the national security, health, and engineering solutions specialist released disappointing preliminary third-quarter results and lowered its full-year guidance.

So what: Quarterly revenues are expected to fall 15% year over year to $1.42 billion, which is well short of analysts' expectations for sales of $1.45 billion. This, in turn, should translate to a $7 million operating loss, compared with operating income of $101 million in the same year-ago period.

As a result, Leidos lowered its fiscal 2014 revenue guidance to a range of $5.65 billion to $5.8 billion, down from the previous range of $5.85 billion to $6.1 billion. In addition, Leidos now expects diluted earnings per share from continuing operations of $0.85 to $1.10, compared to the previous range of $1.80 to $2.04.

By comparison, analysts were looking for fiscal 2014 earnings of $1.89 per share on sales of $5.93 billion.

Now what: Leidos blamed the decrease in revenue both on the temporary government shutdown and "market conditions more challenging than previously expected."

What's more, the company stated its operating loss is primarily due to a number of exceptional expenses, including a $42 million bad debt expense related to its Plainfield and Gradient energy construction projects, separation and restructuring expenses of $25 million related to the spin-off of SAIC's services business, a $19 million asset impairment charge from two commercial health acquisitions, and $5 million in reserves for "discrete regulatory and legal matters."

As it stands, however, the stock does look cheap trading around 8.3 times last year's earnings and roughly 13 times next year's estimates. What's more, consider the fact Leidos offers a solid 2.6% dividend to reward shareholders for their patience while Leidos' long-term plans come to fruition. While I wouldn't go all-in even at today's prices, I think this pullback could be a great chance for patient investors to open a small initial position.

Fool contributor Steve Symington has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.