diff --git a/crates/fidc-core/src/platform_expr_strategy.rs b/crates/fidc-core/src/platform_expr_strategy.rs
index 030b3b1..b034754 100644
--- a/crates/fidc-core/src/platform_expr_strategy.rs
+++ b/crates/fidc-core/src/platform_expr_strategy.rs
@@ -9397,12 +9397,8 @@ impl Strategy for PlatformExprStrategy {
                     projected.cash()
                 }
             };
-            let fixed_buy_cash = if self.config.aiquant_transaction_cost {
-                aiquant_available_cash * trading_ratio / selection_limit as f64
-            } else {
-                aiquant_total_value * trading_ratio / selection_limit as f64
-            };
             let target_budget = aiquant_total_value * trading_ratio;
+            let fixed_buy_cash = target_budget / selection_limit as f64;
             let mut rebalance_working_symbols = slot_working_symbols.clone();
             if self.config.release_slot_on_exit_signal {
                 for symbol in &same_day_sold_symbols {
@@ -25285,7 +25281,7 @@ mod tests {
     }
 
     #[test]
-    fn platform_aiquant_periodic_rebalance_uses_cash_divided_by_top_n_buy_budget() {
+    fn platform_aiquant_periodic_rebalance_uses_total_equity_equal_weight_buy_budget() {
         let prev_date = d(2025, 5, 13);
         let date = d(2025, 5, 14);
         let retained_symbols = (1..=17)
@@ -25484,12 +25480,28 @@ mod tests {
             "{:?}",
             decision.order_intents
         );
+        let periodic_buy_values = decision
+            .order_intents
+            .iter()
+            .filter_map(|intent| match intent {
+                OrderIntent::Value { value, reason, .. }
+                    if reason == "periodic_rebalance_buy" => Some(*value),
+                _ => None,
+            })
+            .collect::<Vec<_>>();
+        let equal_weight_target = 5_060_000.0 / 40.0;
         assert!(
-            decision.order_intents.iter().all(|intent| match intent {
-                OrderIntent::Value { value, reason, .. } if reason == "periodic_rebalance_buy" =>
-                    (*value - 75_444.8).abs() < 1e-6,
-                _ => true,
-            }),
+            periodic_buy_values
+                .iter()
+                .take(periodic_buy_values.len().saturating_sub(1))
+                .all(|value| (*value - equal_weight_target).abs() < 1e-6),
+            "{:?}",
+            decision.order_intents
+        );
+        assert!(
+            periodic_buy_values
+                .last()
+                .is_some_and(|value| *value > 0.0 && *value <= equal_weight_target),
             "{:?}",
             decision.order_intents
         );
@@ -25646,7 +25658,7 @@ mod tests {
                     reason,
                 } if symbol == "000002.SZ"
                     && reason == "periodic_rebalance_buy"
-                    && (*value - 5_000.0).abs() < 1e-6
+                    && (*value - 10_000.0).abs() < 1e-6
             )),
             "{:?}",
             decision.order_intents