ironSource is dark. Where the supply went

The ironSource Ads network's direct-demand business shut down today, as announced on March 26 to 27 alongside Unity's decision to explore a sale of the Supersonic publishing label. Advertisers can still pull historical reporting data through May 31, but no new bids, no new impressions, no new fill from this network from this point forward. UA Ledger covered the run-up back when the shutdown was first announced, in a piece built around a 30-day migration checklist for buyers, and today is the deadline that checklist was counting down to.

What actually happened operationally

For any account that had not already moved budget off ironSource, campaigns running through it stopped delivering today, and not gradually. There is no soft wind-down of bid density. Any mediation waterfall or DSP allocation that still has ironSource lines active needs those lines pulled, or they will sit dark, reporting zero spend against zero installs. That is a different failure mode from underperformance, and worth telling apart in a dashboard review this week.

Where the supply actually went

Unity's own results through the first quarter pointed toward Unity Vector, the AI-driven bidding product that Unity has been steering Grow revenue toward, which posted a third straight quarter of mid-teens sequential growth as of the February results; Unity explicitly framed it as the redirection target for the ironSource shutdown. Publishers who ran ironSource mediation on their supply side have had over a month's notice to move that inventory into Unity Vector or LevelPlay, or onto a competing mediation stack. Buyers should not assume the inventory evaporated. It moved, and the practical task is finding where.

For most mid-size buyers, the honest answer is that some of that supply is now reachable through Unity Vector directly, some through AppLovin's Axon and Moloco, both of which compete for the same publisher-side inventory, and some through mediation stacks that quietly reallocated ironSource's share to other demand partners without much announcement.

What to check this week

A short list, before end of month.

Confirm every ironSource line item in every mediation waterfall and DSP has actually stopped rather than paused, because a stopped-but-not-removed line can create reporting confusion for weeks.

Pull the last full month of ironSource reporting before the May 31 data cutoff. Attribution partners will not backfill this once the window closes, and a quarter-over-quarter performance review done in June without that data will show a visible gap.

Rebuild the mediation waterfall assumption. If ironSource previously filled a meaningful share of low-value inventory that other networks did not bid competitively for, its absence may show up as a fill-rate gap rather than a straightforward reallocation, and that gap is worth measuring rather than assuming away.

The shutdown was well-telegraphed. The operational cleanup, checking every account for a line item nobody remembered to remove, is the less glamorous work that actually determines whether Q2 reporting comes out clean.

One longer-term signal sits outside this week's checklist. Unity chose to redirect focus rather than sell or wind the network down gradually, and it is now exploring a sale of Supersonic on top of that. This is a company narrowing its ad business around a single product instead of running several in parallel. Buyers who valued ironSource specifically for its publisher relationships and mediation reach, as distinct from Unity Vector's bidding technology, should read today as the point where that particular offer stopped existing rather than paused.

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