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Payments M&A glossary

MID (Merchant Identification Number)

The unique identifier assigned to each merchant by a payment processor. The unit of measurement for portfolio size.

Also known as
Merchant ID ยท Merchant Identification Number

Full definition

A Merchant Identification Number (MID) is the unique identifier a payment processor assigns to each merchant account. Portfolio size and value in M&A is often discussed in terms of MID count alongside net monthly residual. Active MIDs (those actually processing) are what matters for valuation, as opposed to total or churned MIDs.

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