diff --git a/config/training/dqn-production.toml b/config/training/dqn-production.toml
index 2720654a1..fe765d8e0 100644
--- a/config/training/dqn-production.toml
+++ b/config/training/dqn-production.toml
@@ -36,6 +36,10 @@ trades_data_dir = "/data/futures-baseline-trades"
 
 [distributional]
 num_atoms = 51
+# gamma=0.99 → Q_max = R/(1-gamma) = 100 for unit-variance PopArt rewards.
+# ±50 covers the 95th percentile of Q distribution (±15 default only covers 15%).
+v_min = -50.0
+v_max = 50.0
 
 [exploration]
 epsilon_start = 0.3
diff --git a/config/training/dqn-smoketest.toml b/config/training/dqn-smoketest.toml
index 1821ea955..a8c383819 100644
--- a/config/training/dqn-smoketest.toml
+++ b/config/training/dqn-smoketest.toml
@@ -30,6 +30,10 @@ imbalance_bar_ewma_alpha = 0.1
 
 [distributional]
 num_atoms = 51
+# gamma=0.95 → Q_max = R/(1-gamma) = 20 for PopArt-normalized rewards.
+# ±15 covers 75% of theoretical Q range — adequate for smoke test.
+v_min = -15.0
+v_max = 15.0
 
 [exploration]
 epsilon_start = 0.3
diff --git a/crates/ml/src/cuda_pipeline/gpu_dqn_trainer.rs b/crates/ml/src/cuda_pipeline/gpu_dqn_trainer.rs
index 2ea122120..09e591701 100644
--- a/crates/ml/src/cuda_pipeline/gpu_dqn_trainer.rs
+++ b/crates/ml/src/cuda_pipeline/gpu_dqn_trainer.rs
@@ -942,7 +942,16 @@ impl GpuDqnTrainer {
             .map_err(|e| MLError::ModelError(format!("reset iqn t: {e}")))?;
         self.iqn_trunk_adam_step = 0;
 
-        tracing::info!("Adam optimizer state reset for new fold");
+        // Reset PopArt running statistics — prevents fold 1's reward distribution
+        // from contaminating fold 2's normalization.
+        self.stream.memset_zeros(&mut self.popart_mean)
+            .map_err(|e| MLError::ModelError(format!("reset popart_mean: {e}")))?;
+        self.stream.memset_zeros(&mut self.popart_var)
+            .map_err(|e| MLError::ModelError(format!("reset popart_var: {e}")))?;
+        self.stream.memset_zeros(&mut self.popart_count)
+            .map_err(|e| MLError::ModelError(format!("reset popart_count: {e}")))?;
+
+        tracing::info!("Adam optimizer + PopArt state reset for new fold");
         Ok(())
     }
 }