Criteo dropped 2% yesterday on a report that Facebook had closed its ad exchange to third party tech companies.

But Criteo (NSDQ: CRTO) remains a strong partner to Facebook with its dynamic product advertising software that matches relevant ads to users. In any case, the particular ad exchange (named FBX) that Facebook closed, and which Criteo was involved in, generated little revenue.

Friederike Edelmann, a Criteo executive, confirmed to me this morning that less than 3% of net revenue comes via FBX and that Criteo’s relationship with Facebook remains healthy in mobile and Instagram, the areas with fastest traffic growth.

The closing of Facebook’s ad exchange has been long anticipated. Press releases discussing the closure were issued as early as January of this year. This ad exchange sold space to advertisers only for Facebook desktop and is not related to sales of advertising for Facebook’s mobile app, native advertising (ads buried in news stories) or Instagram.

Criteo is up 18% since we recommended it in early March, and we recommend you buy Criteo on any weakness.