MediaMath

Overview

MediaMath was a pioneering demand-side platform (DSP) that provided agencies and brands with programmatic buying infrastructure for display, video, and native advertising campaigns. Founded in 2007, MediaMath was among the first independent DSPs and operated one of the largest programmatic buying platforms globally. MediaMath filed for Chapter 7 bankruptcy in June 2023 and ceased operations; its technology assets were subsequently acquired. Scripts or pixels associated with MediaMath domains may still appear in legacy tag deployments on advertiser and publisher websites where the original tags have not been cleaned up.

If MediaMath scripts are still firing on a website, they are residual tags from campaigns or integrations that were set up before MediaMath's closure. No active campaign management or bidding occurs through these legacy tags.

What This Script Does

Prior to MediaMath's closure, its scripts operated as a DSP attribution and audience pixel stack:

Scripts / pixels loaded: Attribution and conversion pixels loading from pixel.mathtag.com — MediaMath's cookie sync and tracking domain. Audience sync pixels fired to sync.mathtag.com for cross-platform user ID matching.

Cookies set:

• uuid2 — Third-party persistent cookie on mathtag.com. Stored MediaMath's pseudonymous user identifier for cross-site audience recognition, retargeting, and bid-level user matching. Expiry: 13 months.
• cm — Third-party persistent cookie on mathtag.com. Cookie match table for ID syncing with partner platforms. Expiry: 13 months.
• Sync pixels fired to partner DSPs, SSPs, and DMPs for cross-platform identity bridging.

Data collected per pixel fire:

• Page URL and referrer
• IP address and approximate geolocation
• User-Agent string and browser characteristics
• MediaMath user identifier from the uuid2 cookie
• Conversion event data: event type, order value, product categories
• Audience segment signals for DSP targeting

Current status: With MediaMath no longer operational, active bidding and campaign management has ceased. However, legacy mathtag.com pixels may still fire on websites where the tag has not been removed. These legacy pixels collect data to domains that may be under new ownership or inactive, creating uncontrolled data flows with uncertain recipients.

Consent & Compliance

Consent category: Marketing

MediaMath's tracking pixels set persistent third-party cookies and collected cross-site behavioural data for programmatic advertising. Even as legacy tags, they require the same consent treatment as active advertising scripts.

Under GDPR and ePrivacy, legacy MediaMath pixels still represent non-essential cookie-setting code that requires prior consent before loading. The fact that the company has ceased operations does not eliminate the consent requirement — the cookies and data transmissions still occur.

Under CCPA/CPRA, legacy pixel firing constitutes ongoing collection and (potentially) sharing of personal information, even if the original business purpose no longer applies. Legacy tags with uncertain data destinations are a compliance risk.

Practical recommendation: Any website still carrying MediaMath pixel tags should remove them immediately. With MediaMath's infrastructure under uncertain ownership post-bankruptcy, these tags represent both a compliance risk and a security concern.

Should You Block This Without Consent?

Yes. MediaMath pixels are advertising infrastructure that sets persistent third-party tracking cookies. Block until marketing consent is granted — and review whether these legacy tags should be removed from the site entirely given MediaMath's operational closure.