diff --git a/api/v1_users_balance_history.go b/api/v1_users_balance_history.go
index fa8f5341..91e81c16 100644
--- a/api/v1_users_balance_history.go
+++ b/api/v1_users_balance_history.go
@@ -96,27 +96,37 @@ func (app *ApiServer) v1UsersBalanceHistory(c *fiber.Ctx) error {
 		return err
 	}
 
-	// Build SQL query with granularity parameter
-	// Using a CTE to handle the conditional truncation based on granularity
+	// Build SQL query with granularity parameter.
+	// First sum balance_usd across mints at each hourly snapshot to get the
+	// total portfolio value per hour. For 'daily', pick the latest hour within
+	// each day (end-of-day balance) — do NOT sum balances across hours, since
+	// each hour is a point-in-time snapshot, not an additive quantity.
 	sql := `
-		WITH time_buckets AS (
+		WITH hourly_totals AS (
+			SELECT
+				timestamp,
+				SUM(balance_usd) AS balance_usd
+			FROM user_balance_history
+			WHERE user_id = @user_id
+				AND timestamp >= @start_time
+				AND timestamp <= @end_time
+			GROUP BY timestamp
+		),
+		bucketed AS (
 			SELECT
 				CASE
 					WHEN @granularity::text = 'daily' THEN date_trunc('day', timestamp)
 					ELSE timestamp
 				END AS bucket_timestamp,
+				timestamp AS source_timestamp,
 				balance_usd
-			FROM user_balance_history
-			WHERE user_id = @user_id
-				AND timestamp >= @start_time
-				AND timestamp <= @end_time
+			FROM hourly_totals
 		)
-		SELECT
+		SELECT DISTINCT ON (bucket_timestamp)
 			bucket_timestamp AS timestamp,
-			SUM(balance_usd) AS balance_usd
-		FROM time_buckets
-		GROUP BY bucket_timestamp
-		ORDER BY bucket_timestamp ASC
+			balance_usd
+		FROM bucketed
+		ORDER BY bucket_timestamp ASC, source_timestamp DESC
 	`
 
 	rows, err := app.pool.Query(c.Context(), sql, pgx.NamedArgs{
diff --git a/api/v1_users_balance_history_test.go b/api/v1_users_balance_history_test.go
index e4be1466..1bfd85d4 100644
--- a/api/v1_users_balance_history_test.go
+++ b/api/v1_users_balance_history_test.go
@@ -538,13 +538,15 @@ func TestUserBalanceHistoryDailyGranularityWithMultipleHours(t *testing.T) {
 		"data.#": 3, // 3 hourly points
 	})
 
-	// Test daily granularity - should return 1 data point with summed balance
+	// Test daily granularity - should return 1 data point representing the
+	// balance at the latest hour of the day (end-of-day balance), not a sum
+	// across all hours (each row is a point-in-time portfolio snapshot).
 	status, body = testGet(t, app, "/v1/users/"+trashid.MustEncodeHashID(1)+"/balance/history?start_time="+startTime+"&end_time="+endTime+"&granularity=daily")
 	assert.Equal(t, 200, status)
 
 	jsonAssert(t, body, map[string]any{
-		"data.#":             1,    // 1 daily point (all hours on same day grouped)
-		"data.0.balance_usd": 60.0, // Sum: 10 + 20 + 30
+		"data.#":             1,    // 1 daily point (latest hour of the day)
+		"data.0.balance_usd": 30.0, // Balance at 18:00 (the latest hour)
 	})
 }