It has been about a month since the last earnings report for Clean Harbors (CLH). Shares have lost about 1.9% in that time frame, underperforming the S&P 500.Will the recent negative trend continue leading up to its next earnings release, or is Clean Harbors 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 drivers. Clean Harbors' Q4 Earnings Beat Estimates, Revenues MissClean Harbors reported mixed fourth-quarter 2020 results wherein earnings surpassed the Zacks Consensus Estimate but revenues missed the same.Adjusted earnings per share of 63 cents outpaced the Zacks Consensus Estimate by 70.3% and increased 50% year over year. Total revenues of $796.2 million missed the consensus mark by 0.8% and declined 8.6% year over year due to the unprecedented market conditions.Revenues by SegmentEnvironmental Services revenues of $546.06 million declined 5.5% year over year. Safety-Kleen revenues of $250.79 million fell 14.6% year over year.Profitability PerformanceAdjusted EBITDA of $136.06 million increased 2.9% year over year. Adjusted EBITDA margin increased 190 basis points (bps) year over year to 17.1%.Segment wise, Environmental Services’ adjusted EBITDA was $132.11 million, up 12.7% year over year. Safety-Kleen’s adjusted EBITDA of $52.67 million declined 21.1% year over year.Balance Sheet & Cash FlowClean Harbors exited fourth-quarter 2020 with cash and cash equivalents of $519.1 million compared with $475.7 million at the end of the prior quarter. Inventories and supplies were $220.49 million compared with $220.9 million in the prior quarter. Long-term debt of $1.55 billion was flat sequentially.The company generated $113.17 million in net cash from operating activities in the reported quarter. Adjusted free cash flow was $69.58 million.2021 GuidanceClean Harbors expects adjusted EBITDA in the range of $545-$585 million. Net income is anticipated to be in the band of $105-$146 million. Adjusted free cash flow is expected between $215 million and $255 million. Net cash from operating activities is projected between $400 million and $460 million.How Have Estimates Been Moving Since Then?In the past month, investors have witnessed an upward trend in estimates review.VGM ScoresAt this time, Clean Harbors has a strong Growth Score of A, a grade with the same score on the momentum front. Charting a somewhat similar path, the stock was allocated a grade of B on the value side, putting it in the top 40% 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 broadly trending upward for the stock, and the magnitude of these revisions looks promising. Notably, Clean Harbors has a Zacks Rank #3 (Hold). We expect an in-line 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 Clean Harbors, Inc. (CLH): Get Free Report To read this article on Zacks.com click here.