Business lost to the pandemic has rebounded for StockX, an online marketplace where people selling and buying items -- sneakers, mainly -- negotiate on a price before StockX provides authentication and shipping.

"We've seen an incredible return to activity in the marketplace," StockX CMO Deena Bahri said on the Modern Retail Podcast. "By mid-April we started to see an incredible return back to normal -- and even better than normal -- shopping behaviors."

That's the case even though the company cut its spending on "anything that's not directly attributable to measurable growth," Bahri said. StockX reduced its spending on linear TV and marketing at cultural events.

"The more conservative stance on marketing spend has not had a negative impact on business, very fortunately," Bahri said.

The Detroit-based company was founded in 2015 with an exclusive focus on sneakers. It's diversified into other streetwear, watches, trading cards and electronics. But shoes are still the main attraction.

Sneakerheads and other consumers may even be turning to shoes as smart investments. A scrolling tape across the bottom of StockX's homepage announces which footwear is up or down in the market. "Our trend partners that we work with, and some of the things we've observed on our own, indicate that people are more prone during a time like this to spend on things that are investments, classics, items that will endure," Bahri said.