What does gross-to-net mean in pharma?

Gross-to-net is the difference between a drug list (WAC) price and the actual price realized by the manufacturer after rebates, chargebacks, discounts, and fees are deducted. For many branded drugs, the gross-to-net gap can be 50% or more, meaning the manufacturer realizes less than half the list price. This gap has been growing steadily as rebate demands increase.