It has been about a month since the last earnings report for AutoZone (AZO). Shares have lost about 5.3% in that time frame, underperforming the S&P 500.Will the recent negative trend continue leading up to its next earnings release, or is AutoZone due for a breakout? Before we dive into how investors and analysts have reacted as of late, let's take a quick look at its most recent earnings report in order to get a better handle on the important catalysts. AutoZone Q4 Earnings Top Estimates, Revenues In LineAutoZone has reported adjusted earnings of $18.54 per share in the fourth quarter of fiscal 2018 (ended Aug 25, 2018), beating the Zacks Consensus Estimate of $17.88. The figure was $15.27 in fourth-quarter fiscal 2017.For fiscal 2018, adjusted earnings per share increased year over year from $44.07 to $48.77.Revenues improved 1.3% year over year to $3.6 billion in the reported quarter and it was almost in-line with the Zacks Consensus Estimate. Domestic same-store sales (sales of stores open at least for a year) rose 2.2% year over year.For fiscal 2018, the company's revenues rose to $11.2 billion compared with the last fiscal’s figure of $10.8 billion.Gross profit increased to $1.91 billion from $1.85 billion in the prior-year quarter. Operating profit (EBIT) rose to $54.3 million from $51.4 million registered in the fourth quarter of fiscal 2017.Operating expenses, as a percentage of sales, increased to 37% from 32.6% a year ago. This rise is primarily due to charges associated with the termination of pension plans of $130.3 million and domestic store payroll.Store Opening & InventoryDuring the quarter ended Aug 25, AutoZone opened 78 stores and relocated four in the United States. The company also opened 28 stores in Mexico and four in Brazil. As of Aug 25, it had 5,618 stores across 50 states in the United States, the District of Columbia and Puerto Rico; 564 in Mexico; and 20 in Brazil. The total store count was 6,202 as of that date.AutoZone’s inventory improved 1.6% year over year in the quarter under review, driven by store openings and increased product placement, partially offset by the sale of two business units. At the end of fiscal 2018, inventory per location increased to $636,000 from the year-ago figure of $644,000.Share RepurchasesIn the fourth quarter of fiscal 2018, AutoZone repurchased 974,000 shares for $665 million, reflecting an average price of $683 per share. The company had shares worth $232 million remaining for repurchase at the end of fiscal 2018.Financial DetailsAutoZone had cash and cash equivalents of $217.8 million as of Aug 25, 2018, down from $293.3 million as of Aug 26, 2017. Total debt amounted to $5 billion as of Aug 25, 2018, almost in-line with the figure recorded on Aug 26, 2017.How Have Estimates Been Moving Since Then?In the past month, investors have witnessed an upward trend in fresh estimates.VGM ScoresCurrently, AutoZone has a nice Growth Score of B, however its Momentum Score is doing a bit better with an A. Charting a somewhat similar path, the stock was allocated a grade of B on the value side, putting it in the second quintile for this investment strategy.Overall, the stock has an aggregate VGM Score of A. If you aren't focused on one strategy, this score is the one you should be interested in.OutlookEstimates have been trending upward for the stock, and the magnitude of these revisions looks promising. It comes with little surprise AutoZone has a Zacks Rank #2 (Buy). We expect an above average return from the stock in the next few months.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 AutoZone, Inc. (AZO): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research