GoodRx shares plummeted more than 20% Tuesday after Amazon announced its plunging into the pharmacy space with delivery prescriptions.

Amazon, which acquired online pharmacy PillPack in 2018, is attempting to go head to head with big-box retailers with service currently in 45 states.

The news rippled through the industry sending shares of CVS, Walgreens and Rite Aid tumbling but it especially slammed discount prescription app GoodRx, which depends on all those for its business.

Amazon Pharmacy accepts insurance but also is appealing to those without insurance, the same market that GoodRx caters to with its comparison drug pricing for different pharmacies.

The Seattle retail giant will offer Prime members without insurance discounts of up to 80% off generic drugs and 40% off brand name medications at its pharmacy and through 50,000 additional pharmacies nationally. And it promises members free two-day delivery. It will not deliver opioids.

GoodRx, which made its Wall Street debut this year, acknowledged in Securities and Exchange Commission filings that one of the larger threats to their business is a shift toward mail order drugs.

Earlier this month, GoodRx forecast 40% year-over-year revenue growth next year.