The stock of Northrop Grumman (NOC -13.62%) is getting hit with big sell-offs Tuesday following the company's recently published first-quarter results. The share price was down 11.4% as of noon ET today amid the backdrop of a 1.9% gain for the S&P 500.Northrop posted its first-quarter Q1 results before the market opened this morning, and both sales and earnings fell short of Wall Street's expectations. In addition to weaker-than-anticipated performance last quarter, the company also lowered its full-year pe ...