Profit declined 15.89 percent year-over-year to $13.03 million and sales fell 12.12 percent from the same quarter in 2014 to $393 million.
Wall Street analysts forecasted $413.38 million in third quarter revenue.
The company also adjusted its full-year earnings outlook to between $1.35 and $1.38 per share from the prior $1.35-to-$1.41 range and revenue to between $1.55 billion and $1.6 billion from the prior $1.55 billion-to-$1.65 billion forecast.
ManTech reported earnings of $1.27 per share and $1.77 billion in sales for 2014.
Overall backlog as of Sept. 30 was $4.1 billion, 17.14 percent higher than reported in the same period for 2014,  and $900 million was funded to hold level from last year’s figure.
ManTech shares have declined 7.02 percent from the year’s start and are down 1.02 percent over 12 months.