Looking back · SecondSource call, July 31

Anthropic kept Sonnet 5's promo price as regular

SecondSource put the odds at about 85% that Claude Sonnet 5 would return to its original price after the promotion ended, and the price didn't go back. Anthropic turned Sonnet 5's limited-time price into the regular price, and the expiry date in the announcement was not enforced. Anthropic's promotional API price for Sonnet 5 was US$2 input and US$10 output per million tokens, due to return to US$3 and US$15 on September 1; on September 30 the official pricing page stated that the promotional price had become the regular price. This was the highest estimate in that set of calls, and the mistake was reading an expiry date as evidence of pricing power. The original price is 50% above the promotional one, US$3 against US$2 for input and US$15 against US$10 for output; at heavy usage, a unit-price gap that size means redoing a gross-margin model (card). How we checked →

Concept illustration: on the left, a long-haired person in a long black coat stands facing right, with a thought bubble above their head showing three round discs on a tray; at the center, a grey board lettered "SONNET 5" stands on a counter with a tray holding two round discs in front of it. On the right, a person in black wearing a lanyard badge leans over and holds with both hands a red-framed black sign lettered "OFFICIAL PRICE" on the front of the counter, a string tag lettered "PROMO PRICE" lies on the floor in front of the counter, and the beige wall behind shows a black angular shape beside the lettering "ANTHROPIC".

Source and checks

This item ran in the brief of Nov 1, 2026, alongside 7 other items. How we checked it, the quote checks and what was still missing that day are on that issue's How we checked page.

Cite this item

SecondSource (2026). "Anthropic kept Sonnet 5's promo price as regular." https://secondsource.io/en/news/2026-11-01-3/. Accessed access date.