ATACMS can be fitted with an HE warhead or multiple cluster munitions
Three different types of warheads are used on the operational models of the ATACMS. The MGM-140A contains 950 M74 APAM (Anti-Personnel Anti-Material) submunitions, which are scattered in mid-air during the final stretch of the missile's terminal phase. Depending on how far from the target the missile is set to release its submunitions, they can potentially saturate an area of up to 33 000 m2, with each submunition having a casualty radius of 15 m. The MGM-140B disperses the same M74 submunitions, but carries roughly one-quarter as many. The MGM-168A carries a large unitary warhead designed to greatly increase damage to point targets, while minimizing collateral damage. All three of these warheads are most effective when employed against soft targets.
MGM-168A: Replaces submunitions with a 227 kg WDU-18/B unitary high-explosive warhead. Also has a greatly improved range over the MGM-140B. Formerly designated the MGM-140E.
https://www.militarytoday.com/missiles/atacms.htm
https://missilethreat.csis.org/missile/atacms/