Petco Health & Wellness Co. shares plunged as much as 18% in postmarket trading following the company's second-quarter forecast that disappointed investors. The guidance fell below consensus estimates, overshadowing what had been a stronger first quarter performance. This sudden reversal highlights the market's sensitivity to future projections even when current results show improvement.

The retailer had just reported better-than-expected first quarter results, marking a significant milestone with positive revenue growth for the first time in nearly two years. Despite this achievement, investors focused on the disappointing second-quarter outlook, which apparently failed to meet analysts' expectations for the upcoming period.

The dramatic stock movement underscores Wall Street's skepticism about Petco's recovery narrative. The company's inability to maintain positive momentum into the next quarter suggests the turnaround remains incomplete. Investors clearly value forward-looking guidance more than past improvements in this case, punishing the stock despite recent operational progress.