Potbelly (PBPB) shares ended the last trading session 6.7% higher at $8.26. The jump came on an impressive volume with a higher-than-average number of shares changing hands in the session. This compares to the stock's 7.4% gain over the past four weeks.Sequential improvement in same-store sales, solid Traffic-Driven Profitability’ strategic plan, operational improvements, and ongoing recovery in the macro-economic environment have been boosting investors’ confidence.This sandwich restaurant operator is expected to post quarterly loss of $0.17 per share in its upcoming report, which represents a year-over-year change of +73%. Revenues are expected to be $99.85 million, up 77.8% from the year-ago quarter.While earnings and revenue growth expectations are important in evaluating the potential strength in a stock, empirical research shows a strong correlation between trends in earnings estimate revisions and near-term stock price movements.For Potbelly, the consensus EPS estimate for the quarter has been revised 2.9% higher over the last 30 days to the current level. And a positive trend in earnings estimate revision usually translates into price appreciation. So, make sure to keep an eye on PBPB going forward to see if this recent jump can turn into more strength down the road.The stock currently carries a Zacks Rank 3 (Hold). You can see the complete list of today's Zacks Rank #1 (Strong Buy) stocks here >>>>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 Potbelly Corporation (PBPB): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research