It may be time to buy shares of Carvana , according to Piper Sandler. Analyst Alexander Potter upgraded the online used car retailer to overweight from neutral, saying that the stock is too cheap to ignore and could double from current levels. "Before we get to the punchline, please note that yes, we are aware that used vehicle prices are falling. We know that rising interest rates are a risk, and we know that bankruptcy is a real possibility. But CVNA is now 1/10th as valuable as it was 12 months ago, and after running a detailed sensitivity analysis (pages 7-16), we think many realistic scenarios suggest that CVNA is grossly undervalued," Potter wrote in a Sunday note. "CVNA could easily continue falling, but with so much potential upside, we think investors should consider owning at least some CVNA," the analyst added. The stock is down 84% this year and 89% off its 52-week high, as Carvana accelerated growth just as consumer demand started slowing down. Carvana bought a record number of vehicles last year in anticipation of greater demand. The $73 price target is about 99.3% above where shares closed Friday at $36.62. The stock jumped nearly 6% in Monday premarket trading. —CNBC's Michael Bloom contributed to this report.