Sullivan & Cromwell, Simpson Thacher & Bartlett and Latham & Watkins are playing lead roles in the planned merger of financial services technology provider Fiserv and First Data Corp., a leading processor of credit and debit card transactions.

The deal, an all-stock transaction, has a projected equity value of $22 billion. Under the deal’s terms, Fiserv will acquire First Data, whose shareholders will receive 0.303 Fiserv shares for each unit of First Data common stock they hold. Fiserv shareholders will come away from the deal with ownership of 57.5 percent and First Data shareholders with 42.5 percent of the new entity.