It has been about a month since the last earnings report for Ultragenyx (RARE). Shares have lost about 7.8% in that time frame, underperforming the S&P 500.Will the recent negative trend continue leading up to its next earnings release, or is Ultragenyx 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. Ultragenyx Q1 Loss Narrows Y/Y, Revenues Beat EstimatesUltragenyx reported first-quarter 2021 loss per share of $2.03 compared with a loss of $2.05 in the year-ago quarter. The Zacks Consensus Estimate was pegged at a loss of $1.25 per share.In the first quarter, Ultragenyx reported total revenues of $99.4 million, up 173.7% from the year-ago quarter driven by strong launches for Dojolvi and Crysvita for the second indication. The top line surpassed the Zacks Consensus Estimate of $75 million.Quarter in DeatilUltragenyx markets three drugs, Crysvita, Mepsevii and Dojolvi (UX007). Crysvita is approved for the treatment of X-linked hypophosphatemia, an inherited disorder and tumor induced osteomalacia (TIO), an ultra-rare disease. Mepsevii is approved to treat Mucopolysaccharidosis VII (MPS VII), also known as Sly syndrome. Dojolvi was approved last year for all forms of long-chain fatty acid oxidation disorders (LC-FAOD).Crysvita’s total revenues were $46.0 million, up 46.3% year over year driven by increased demand for both approved indications. Crysvita revenues in Ultragenyx territories rose 46% to $42.1 million in the quarter and included $36.3 million from the North America profit share territory and $5.9 million of net product sales for the drug in other regions. Total royalty revenues related to the sales of Crysvita in the European Territory were $3.9 million.Mepsevii product revenues were $3.6 million in the quarter, up 5.3% year over year. Dojolvi (UX007) product revenues were $7.0 million versus $1.44 million in the year-ago quarter driven by strong new patient demand. Revenues in the quarter also included $42.8 million related to the collaboration and license agreement with Daiichi Sankyo for Ultragenyx’s proprietary AAV-based gene therapy manufacturing technologies.Operating expenses rose 31% to $206 million in the quarter.2021 GuidanceThe company reaffirmed the guidance for Crysvita which it provided at the beginning of 2021 when it released preliminary sales numbers for the drug. This range is $180 million to $190 million in the Ultragenyx territories, representing growth of 30% to 37% year over year. R&D and SG&A costs are expected to increase in 2021 as the company supports its expanding pipeline and launches of Crysvita, Dojolvi and Mepsevii.How Have Estimates Been Moving Since Then?It turns out, estimates revision flatlined during the past month.VGM ScoresCurrently, Ultragenyx has a poor Growth Score of F, however its Momentum Score is doing a lot better with a B. However, the stock was allocated a grade of D on the value side, putting it in the bottom 40% for this investment strategy.Overall, the stock has an aggregate VGM Score of F. If you aren't focused on one strategy, this score is the one you should be interested in.OutlookUltragenyx has a Zacks Rank #4 (Sell). We expect a below 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 Ultragenyx Pharmaceutical Inc. (RARE): Free Stock Analysis Report To read this article on Zacks.com click here.