Price tags on new drugs may be rising. Price hikes on older meds remain regular. But that’s just the superficial view, a new study concludes. Rebates and discounts are taking a big bite out of drug costs — and holding down overall price growth.

Taking rebates and discounts into account, pricing for branded meds in the U.S. grew by less than 1% last quarter, compared with 4.4% during the same period last year, according to the market analysts at SSR.

Thing is, just a few hotly contested drug categories are responsible for that decline. Payers have used their formulary power to pit drugmakers against each other, aiming for price breaks. You know the ones: insulin meds for diabetes, combo drugs for COPD, and antiviral treatments for hepatitis C.