HRM-MoE: Efficient Sparse Pretraining with Hierarchical Reasoning
HRM-MoE is a sparse Mixture-of-Experts extension of HRM-Text. This release is the epoch-4 pretrained 64x8 MoE checkpoint, exported from the native FSDP2 checkpoint into a single bf16 model.safetensors file.
The main point of this checkpoint is sparse activation: the model has 5.41B total parameters, but each token activates only top-8 of 64 experts, for about 1.19B active parameters per token (21.9% of the full parameter pool). In other words, it keeps active compute close to dense HRM-Text-1B while giving the model a much larger expert parameter pool.
This is a pre-alignment base checkpoint. It is not a chat or instruction-following assistant.
Model Structure Comparison
text
1Dense HRM-Text XL / HRM-Text-1B-style FFN
23input tokens
4 -> H/L recurrent HRM blocks
5 -> dense SwiGLU FFN, intermediate width 4096
6 -> all dense FFN parameters are active for every token
78HRM-MoE 64x8
910input tokens
11 -> H/L recurrent HRM blocks
12 -> router over 64 SwiGLU experts
13 -> top-8 experts active per token, each expert width 512
14 -> active FFN width = 8 x 512 = 4096
Model
Total params
Active params / token
Active ratio
FFN path
Dense HRM-Text XL
~1.18B
~1.18B
100%
dense SwiGLU, width 4096
HRM-MoE 64x8
5.41B
~1.19B
21.9%
64 routed SwiGLU experts, top-8, width 512 each
The active FFN width is intentionally matched to the dense XL baseline, while the sparse expert pool increases total capacity.
Results vs Dense HRM-Text
The comparison below uses the same HRM pretraining pipeline, same sampled pretraining data, same 32-GPU setup, and 4 pretraining epochs. Values are percentages unless otherwise noted.
Benchmark
Metric
Dense HRM-Text XL e4
HRM-MoE 64x8 e4
Delta
GSM8k
acc
83.93
84.99
+1.06
MATH
acc
54.96
60.08
+5.12
DROP
em
79.45
80.86
+1.41
DROP
f1
83.06
84.53
+1.47
MMLU
acc
61.38
61.18
-0.20
ARC
acc
83.02
87.80
+4.78
HellaSwag
acc
61.96
73.89
+11.93
Winogrande
acc
71.98
73.88
+1.90
BoolQ
acc
87.25
88.75
+1.50
MMLU-Pro
acc
32.72
37.57
+4.85
AIME25
maj_pass@1
13.33
16.67
+3.34
AIME25
maj_pass@10
36.67
36.67
+0.00
AIME25
maj_pass@100
53.33
56.67
+3.34
Model Details
Field
Value
Architecture
HRM-Text with sparse MoE FFN
Checkpoint
epoch 4 pretrained checkpoint
Format
bf16 model.safetensors
Total parameters
5.41B
Active parameters / token
~1.19B
Non-expert parameters
~0.58B
Expert parameters
~4.83B
Hidden size
1536
Layers per H / L stack
16
Attention heads
12
H_cycles x L_cycles
2 x 3
Max sequence length
4096
Vocabulary
65,536
Position encoding
RoPE theta 10000
Normalization
Parameterless Pre-RMSNorm
Attention
Gated attention
MoE experts
64
MoE top-k
8
Expert intermediate size
512
Active FFN width
8 x 512 = 4096
MoE kernel
grouped Triton expert GEMM
Exported weights
EMA weights
dtype
bfloat16
Requirements
This checkpoint uses the custom hrm_text_moe architecture through Hugging Face trust_remote_code=True.
The remote-code inference path is self-contained and uses PyTorch attention plus grouped expert bmm. Hopper-class GPUs are recommended for practical speed.
This mirrors the HRM-Text-1B usage pattern. The only extra flag is trust_remote_code=True, because hrm_text_moe is not yet a native Transformers architecture.
Prompt Format
HRM-Text and HRM-MoE use condition prefix tokens. Prompts should be rendered as:
For reasoning-style prompting, synth,cot maps to <|quad_end|><|object_ref_end|>.
PrefixLM Mask
The checkpoint was pretrained with the HRM-Text PrefixLM objective. Pass token_type_ids = torch.ones_like(input_ids) for the prompt, marking it as one bidirectional prefix block before autoregressive decoding.
Training Snapshot
32 GPUs
4 pretraining epochs
global batch size 196,608 tokens
learning rate 2.2e-4
bfloat16 forward/backward
EMA decay 0.9999
grouped Triton MoE expert kernels
Limitations
Pre-alignment base checkpoint, not a chat model.
Not instruction-tuned, RLHF-trained, or safety-aligned.
English-focused pretraining mixture.
Requires trust_remote_code=True; CUDA is strongly recommended for practical inference.
This model is derived from HRM-Text. If you use HRM-Text or HRM-MoE, please cite:
bibtex
1@misc{wang2026hrmtextefficientpretrainingscaling,
2 title={HRM-Text: Efficient Pretraining Beyond Scaling},
3 author={Guan Wang and Changling Liu and Chenyu Wang and Cai Zhou and Yuhao Sun and Yifei Wu and Shuai Zhen and Luca Scimeca and Yasin Abbasi Yadkori},
4 year={2026},
5 eprint={2605.20613},
6 archivePrefix={arXiv},
7 primaryClass={cs.CL},
8 url={https://arxiv.org/abs/2605.20613},
9}