# Anthropic says anti-distillation measures may have cut data harvested by 90‑99%

Digest AI · Research · published 2026-10-13T11:06:46Z

Canonical: https://digestai.news/story/anthropic-says-it-cut-claude-reasoning-token-theft-by-up-to-99

## Summary

Anthropic announced that its latest anti‑distillation defenses appear to have lowered the amount of data harvested by illicit distillers by roughly 90 to 99%, according to early evidence. The company says the measures target Claude’s reasoning transcripts, which are the most valuable data for copying model behavior. New safeguards include “preserved thinking” that blocks editing of prior context for new API accounts, a two‑stage classifier with a false‑positive rate of less than 0.1%, and charging for requests blocked by the classifier.

Anthropic reports that these steps have led to tens of thousands of fraudulent accounts being banned, often within two hours, and that the volume of reasoning tokens extracted by distillers is now consistently 10 to 100 times lower than before. The changes have required some developers to update integrations and have caused occasional misidentification of benign requests, but the company argues the trade‑offs are justified to protect national security and prevent the release of powerful models without robust safeguards.

## Key points

- Anthropic reports early evidence that anti‑distillation methods reduced data harvested by distillers by about 90‑99%
- New defenses use preserved thinking, a two‑stage classifier with <0.1% false positives, and charge for blocked requests
- Measures have banned tens of thousands of accounts and cut extracted reasoning tokens 10‑100×, though some legitimate users see integration updates

## Why it matters

Limiting illicit distillation helps keep frontier AI capabilities from being copied without safeguards, reducing national‑security threats and preventing the spread of powerful, unregulated models.

## Sources

1. [Anthropic anti-distillation measures may have reduced data harvest by 90-99%](https://anthropic.com/research/distillation-defenses) (anthropic.com, 2026-10-13, primary source)
2. [Anthropic says it cut Claude reasoning token theft by up to 99% in fight against industrial-scale distillation](https://the-decoder.com/anthropic-says-it-cut-claude-reasoning-token-theft-by-up-to-99-in-fight-against-industrial-scale-distillation) (The Decoder, 2026-10-13)

## Cite

Digest AI, "Anthropic says anti-distillation measures may have cut data harvested by 90‑99%", 13 October 2026, https://digestai.news/story/anthropic-says-it-cut-claude-reasoning-token-theft-by-up-to-99

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