Findings of the WMT 2026 Shared Task on Model Compression: No Free Lunch at Extreme Compression

Thamme Gowda, Marco Gaido, Roman Grundkiewicz, Matteo Negri


Abstract
We present the second edition of the WMT 2026 Model Compression (WMT26MC) shared task, which studies how large language models can be made efficient for machine translation under model-size and latency constraints. WMT26MC offers a constrained track based on Gemma~3~12B and an unconstrained track for compressing models below 20B. Both tracks cover cs-de, en-zh, and en-ar. Participants submit complete runnable systems, which we run in a standardized environment on single H100 GPU. Evaluation jointly considers translation quality, model size on disk, and decoding speed, analyzing the resulting quality–size and quality–speed trade-offs. We received 41 submissions from 13 teams. The proposed systems span weight and activation quantization, structured and expert pruning, low-rank factorization, knowledge distillation, vocabulary and vision-component removal, mixed precision, and inference-time reranking. Evaluating with reference-free quality-estimation metrics on the blind test sets, we find that post-training quantization is the reliable lever: INT4 and FP8 systems shrink the constrained base to roughly a quarter of its on-disk size and run up to an order of magnitude faster while staying within quality-estimation noise of the uncompressed model, whereas aggressive low-rank and structural pruning collapse quality.
Anthology ID:
2026.wmt-main.52
Volume:
Proceedings of the Eleventh Conference on Machine Translation
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Barry Haddow, Tom Kocmi, Philipp Koehn, Christof Monz
Venues:
WMT | WS
SIG:
SIGMT
Publisher:
Association for Computational Linguistics
Note:
Pages:
1080–1090
Language:
URL:
https://aclanthology.org/2026.wmt-main.52/
DOI:
Bibkey:
Cite (ACL):
Thamme Gowda, Marco Gaido, Roman Grundkiewicz, and Matteo Negri. 2026. Findings of the WMT 2026 Shared Task on Model Compression: No Free Lunch at Extreme Compression. In Proceedings of the Eleventh Conference on Machine Translation, pages 1080–1090, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Findings of the WMT 2026 Shared Task on Model Compression: No Free Lunch at Extreme Compression (Gowda et al., WMT 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.wmt-main.52.pdf