Market, not Direct
ymclid comes from Yandex Market. Yandex Metrica's help page on tags gives it one line: "The tag is set by Yandex Market." One letter away sits yclid, which Yandex Direct, Yandex's ad platform, adds to paid ad clicks. The two land in different reports. Direct clicks go to Metrica's Yandex Direct report group, while Yandex points to the Ad systems report for traffic from Yandex Market.
Five Yandex tags that look alike
The same help page lists a whole family, each from a different Yandex product:
- yclid: added by Yandex Direct, reported in the Yandex Direct report group
- ymclid: set by Yandex Market, reported under Ad systems
- ysclid: identifies keywords from Yandex Search, shown in the Keywords report
- yzclid: set by Yandex PromoPages, reported under Ad systems
- yqrid: tracks QR code click-throughs, shown in the Sources, summary report
Yandex's example values are short placeholders, ymclid=123 among them. The parameter name is what tells you which product sent the visitor.
How Market clicks get counted
Metrica's Ad systems report says that to collect statistics on clicks from Yandex Market, the seller uses tags in URL parameters when setting up the campaign in Market. Like every Yandex tag, ymclid is read from the first pageview of a session only. If a redirect drops it before the first tracked page, it is not detected for that session.
Leave it or remove it
Nothing on the product page depends on ymclid, so a shopper can delete it without changing what loads. The cost falls on the store: Metrica no longer sees the Market tag on that visit. Metrica reads Google's click ID too: Yandex lists gclid on the same page and says to find those sources through segmentation.