Vermont this week became the latest in a growing number of states to sue leading pharmacy benefit managers, accusing them of driving up prescription drug prices for patients in to enrich themselves.

Democratic Attorney General Charity Clark said CVS Health's Caremark, Cigna Group's Express Scripts and several of their affiliates pushed patients toward more-expensive drugs even when less-expensive alternatives were available, and then pocketed the extra cost through an opaque system of fees. The lawsuit alleges that these companies violated Vermont's Consumer Protection Act by manipulating the marketplace and reducing access to certain prescription drugs, including lower-cost drugs, through a series of tactics, with no transparency in their decision-making process.