To date, it has secured investment totaling $25m, of which $20m was raised in January last year from Founders Fund and Polaris Venture Partners.

According to PEHub, Quantcast “is looking to raise around $50 million at a $300 million pre-money valuation”, with the report citing an unidentified source. A spokesman said the firm would not be commenting, not even to deny the report.

Quantcast has been building a reputation for itself recently in the online audience measurment space with big-name support coming from the likes of ABC, online video site Hulu and MTV Networks.

Around 80,000 web publishers have signed up to the firm’s Quantified Publisher programme, through which they tag their sites to allow Quantcast to directly count the number of visits each site receives, data for which is then combined with more traditional panel-based data to produce information on reach, frequency, popularity and audience profile.

In April, it moved out of beta with a new service that allows marketers to tag all web-based media they control to measure ad campaign impressions, search activity, brand web site content and specific purchase or conversion events.

Building on both these services, the firm recently launched the Quantcast Media Program – billed as a new way of buying and selling online audiences.

Customer interaction data from marketers’ media campaigns, search activity and brand website visitation is used to work out the audience characteristics of their most valuable consumer segments. “Lookalike models then identify larger, similar consumer groups across the web,” said Quantcast. “Marketers connect with publisher inventory to purchase these audience definitions, in real time, at scale.”