Northrop Grumman (NOC) closed the most recent trading day at $368.18, moving -1.97% from the previous trading session. This move lagged the S&P 500's daily loss of 0.49%. Meanwhile, the Dow lost 0.59%, and the Nasdaq, a tech-heavy index, lost 0.8%.Heading into today, shares of the defense contractor had gained 0.96% over the past month, lagging the Aerospace sector's gain of 6.83% and the S&P 500's gain of 3% in that time.Wall Street will be looking for positivity from NOC as it approaches its next earnings report date. The company is expected to report EPS of $4.74, down 27.52% from the prior-year quarter. Meanwhile, the Zacks Consensus Estimate for revenue is projecting net sales of $8.55 billion, up 5.7% from the year-ago period.Looking at the full year, our Zacks Consensus Estimates suggest analysts are expecting earnings of $19.63 per share and revenue of $34.01 billion. These totals would mark changes of -7.97% and +13.01%, respectively, from last year.Any recent changes to analyst estimates for NOC should also be noted by investors. These revisions typically reflect the latest short-term business trends, which can change frequently. With this in mind, we can consider positive estimate revisions a sign of optimism about the company's business outlook.Our research shows that these estimate changes are directly correlated with near-term stock prices. Investors can capitalize on this by using the Zacks Rank. This model considers these estimate changes and provides a simple, actionable rating system.The Zacks Rank system ranges from #1 (Strong Buy) to #5 (Strong Sell). It has a remarkable, outside-audited track record of success, with #1 stocks delivering an average annual return of +25% since 1988. The Zacks Consensus EPS estimate remained stagnant within the past month. NOC is currently a Zacks Rank #3 (Hold).Valuation is also important, so investors should note that NOC has a Forward P/E ratio of 19.14 right now. This represents a premium compared to its industry's average Forward P/E of 18.53.It is also worth noting that NOC currently has a PEG ratio of 1.54. This metric is used similarly to the famous P/E ratio, but the PEG ratio also takes into account the stock's expected earnings growth rate. NOC's industry had an average PEG ratio of 2.15 as of yesterday's close.The Aerospace - Defense industry is part of the Aerospace sector. This group has a Zacks Industry Rank of 38, putting it in the top 15% of all 250+ industries.The Zacks Industry Rank includes is listed in order from best to worst in terms of the average Zacks Rank of the individual companies within each of these sectors. Our research shows that the top 50% rated industries outperform the bottom half by a factor of 2 to 1.To follow NOC in the coming trading sessions, be sure to utilize Zacks.com.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Northrop Grumman Corporation (NOC): Free Stock Analysis Report To read this article on Zacks.com click here.