A merger between WebMD and Marketing Technology Solutions (MTS) – the parent of QualityHealth.com – has been terminated.

The $50 million merger, announced in mid-September, had been expected to be finalized by Oct. 15. Instead, WebMD has “acquired a minority preferred interest in MTS,” the statement said. Financial terms were not disclosed. A spokesperson for WebMD declined to comment on the details of the failed merger.

WebMD also entered into an advertising services agreement with QualityHealth.com, allowing WebMD to represent a portion of QualityHealth.com’s media inventory. Conversely, QualityHealth.com will have limited access to certain parts of WebMD’s inventory, according to the spokesperson. QualityHealth.com was not immediately available for comment.

Following a merger with Revolution Health, Waterfront Media’s Everyday Health Network topped WebMD in terms of unique visitors for October, according to comScore data. WebMD had previously led the category for nearly 10 years. QualityHealth.com ranked eighth in unique visitors for October, at 7.3 million. Had the WebMD, QualtyHealth.com merger gone through, WebMD would have been in a position to rival Everyday Health’s unique visitor count, and possibly exceed it.

The WebMD Network includes WebMD Health, Medscape, MedicineNet, eMedicine, eMedicine Health, RxList and theHeart.org.