diff --git a/app/api/v1/endpoints/alpaca.py b/app/api/v1/endpoints/alpaca.py
index 6e99e76..88cb702 100644
--- a/app/api/v1/endpoints/alpaca.py
+++ b/app/api/v1/endpoints/alpaca.py
@@ -404,10 +404,13 @@ async def _run_pit_backfill(start_str: str, end_str: str, force: bool) -> None:
             if batch_num == 1 or batch_num % 50 == 0:
                 logger.info(f"PIT backfill batch {batch_num}/{n_batches} | inserted={total_inserted:,}")
 
+            # FINRA "/" → Alpaca "." 변환 후 전송 (미변환 시 Alpaca 400)
+            # reverse_map: 정규화된 Alpaca 심볼 → FINRA 원본 심볼
             reverse_map = {_finra_to_alpaca(s).upper(): s for s in batch}
+            alpaca_batch = [_finra_to_alpaca(s) for s in batch]
             try:
                 raw = await client.get_multi_bars(
-                    symbols=batch, timeframe="1d",
+                    symbols=alpaca_batch, timeframe="1d",
                     start=start_str, end=end_str,
                     adjustment=ADJUSTMENT,
                 )