What happened

Shares of QuinStreet (QNST) jumped on Thursday after the marketing products and technology provider announced its preliminary third-quarter results. Strong revenue growth put the top line well above the average analyst estimate, and the company expects its positive business momentum to continue. The stock was up about 17.3% at 11 a.m. EDT.

So what

QuinStreet forecasts third-quarter revenue of over $115 million, up 45% compared to the prior-year period. The company also sees its adjusted EBITDA margin coming in above 8%. "Our strong and improving financial performance continues to be driven by good results for our clients and media partners, and by our significant competitive advantages," said CEO Doug Valenti.

A rising stock chart.

Image source: Getty Images.

QuinStreet's preliminary report comes one day after a short-seller targeted the stock. Kerrisdale Capital disclosed that it was short the stock on Wednesday, claiming that the company's revenue growth is a sham, driven by malware redirects, bogus leads, and a one-time deal that has plateaued. The short-seller puts the true value of QuinStreet at $5 to $7 per share, well below the current price of around $12 per share.

Now what

Valenti addressed these accusations directly in the company's press release announcing its preliminary results:

We have reviewed the negative report published about QuinStreet by Kerrisdale Capital Management and feel compelled to respond given its invalid claims and conclusions, and its negative impact on our stock price. QuinStreet management has never been contacted by Kerrisdale. We are disappointed they would make such sweeping claims without contacting us. Kerrisdale claims are inaccurate, out-of-context and exaggerated, and their conclusions about our prospects are demonstrably wrong.

QuinStreet will report its full third-quarter results on May 1, and guidance for the fourth quarter will be provided on the subsequent conference call.