diff --git a/crates/fidc-core/src/corporate_book.rs b/crates/fidc-core/src/corporate_book.rs
index f472871..c8601c1 100644
--- a/crates/fidc-core/src/corporate_book.rs
+++ b/crates/fidc-core/src/corporate_book.rs
@@ -828,7 +828,7 @@ mod tests {
         sold.prune_flat_positions();
         apply(date(), &data, &mut sold, &mut Vec::new(), true, true).unwrap();
         assert_eq!(sold.cash_receivables()[0].amount, 50.);
-        assert_eq!(sold.position("000001.SZ").unwrap().quantity, 0);
+        assert!(sold.position("000001.SZ").is_none());
         let mut converted = conversion_book();
         converted.apply_successor_conversion("000001.SZ", "000002.SZ", 2., 0.).unwrap();
         apply(date(), &data, &mut converted, &mut Vec::new(), true, true).unwrap();
diff --git a/crates/fidc-core/src/portfolio.rs b/crates/fidc-core/src/portfolio.rs
index ea308f4..989047b 100644
--- a/crates/fidc-core/src/portfolio.rs
+++ b/crates/fidc-core/src/portfolio.rs
@@ -1214,8 +1214,10 @@ impl PortfolioState {
     pub fn prune_flat_positions(&mut self) {
         let mut sold_symbols = Vec::new();
         for (symbol, position) in &self.positions {
-            self.retired_lot_sequences.entry(symbol.clone()).and_modify(|next| *next=(*next).max(position.next_lot_sequence))
-                .or_insert(position.next_lot_sequence);
+            if position.is_flat() {
+                self.retired_lot_sequences.entry(symbol.clone()).and_modify(|next| *next=(*next).max(position.next_lot_sequence))
+                    .or_insert(position.next_lot_sequence);
+            }
         }
         self.positions.retain(|symbol, position| {
             if position.is_flat() {