AppNexus this week reported that Average CPMs on its platform rose sharply during the second half of 2015, from below 20 cents last summer to $1.60 by early fall, as invalid traffic was rejected under the company's anti-fraud efforts. AdExchanger reports that AppNexus’ Inventory Quality (IQ) initiative to clean up fraudulent or invalid inventory was highly effective. According to the report, the initial 500% price jump that came after the company's fraud purge was followed by a more modest 18% lift in December. “What was more surprising [than the initial slope] is the second increase you see in December, around the holiday season,” AppNexus Chief Data Scientist Catherine Williams told AdExchanger.