According to Recode, Wildcat Capital Management, the family investment firm of billionaire investor David Bonderman, came in as a new backer in the round. Past investors including Kleiner Perkins Caulfield & Byers and Rincon Venture Partners also participated. Tradesy, which is based in Santa Monica, Calif., has now secured nearly $75 million in funding since launching in 2012.

Tradesy and competitors The RealReal and Poshmark have each raised $25 million or more in the last few months to try to help them break away from the pack. All three operate websites and apps that sell lightly used clothing from brands like Tory Burch and Louis Vuitton, as they try to carve out a piece of eBay's business. And all three are in a land grab to attract more consumers to buy and sell on their sites, as shoppers typically end up flocking to sites with the most selection.

'I still think it's winner-take-all and we're still pushing to be the winner,' CEO Tracy DiNunzio said in an interview. 'But whether winner-takes-all means everyone else dies, I don't know.'

Several startups in the second-hand clothing niche have been gobbled up on the cheap in the past year.

Tradesy remains focused on clothing, shoes and bags, DiNunzio noted, while The RealReal has looked for growth by expanding into jewelry and art and Poshmark has started to allow its best sellers to buy clothing from wholesalers at a discount and resell it on the site. Tradesy still gets a good amount of sales from unpaid search traffic, because it has structured listings on its marketplace in a way that makes it easy for search engines to crawl.

Still, like many e-commerce entrepreneurs today, DiNunzio admitted that it was challenging to raise this amount of money in today's investment climate without taking on unfavorable terms.

'We've grown 4x since our last funding on all [metrics], but our valuation did not grow 4x,' she said. She declined to reveal the specific valuation on this investment, but said that it increased from the last round's tally of around $100 million and that the deal did not include unusual and potentially damaging terms.

Tradesy will use the majority of the new funds for hiring, specifically data scientists and taxonomists who are tasked with analyzing the site's shopping data to see how fashion brands might be able to use it. Tradesy will also use the new money to run more national cable TV ad campaigns, which DiNunzio said have been as cost-effective as its online advertising. DiNunzio would not comment on the company's revenue, but said the startup should be profitable on an Ebitda base by the middle of next year.