diff --git a/backend/app/api/reports.py b/backend/app/api/reports.py
index d736f80c..eebd254c 100644
--- a/backend/app/api/reports.py
+++ b/backend/app/api/reports.py
@@ -2418,15 +2418,20 @@ def get_dupont_analysis(
         # 存量/流量缺失时 raw 值为 None（如博海存量仅到区间外）⇒ 显式「-」，不得 None 格式化
         return "-" if v is None else f"{v:.2f}"
 
+    def _fmt_val(v):
+        # 叙述段（恒等式三因子 / ROE / 偏差）表现层口径：缺失同族显式「-」；
+        # 有值时**原样输出**（不经 :.2f，保证有值路径逐字节不变）。
+        return "-" if v is None else v
+
     detail = (f"{label}口径（流量累计 {win['period_start']}~{win['period_end']}，"
               f"存量{'平均' if cur['basis'] == 'average' else '期末回落'}"
               f"{'，年化 ×12/' + str(win['months']) if annualize else '，非年化'}）："
               f"净利润 {_fmt(cur['raw']['net_profit'])}万 / 营业收入 {_fmt(cur['raw']['revenue'])}万 / "
               f"平均总资产 {_fmt(cur['raw']['total_assets'])}万 / 平均净资产 {_fmt(cur['raw']['equity'])}万；"
-              f"ROE = {factors['net_profit_margin']['value']}% × {factors['asset_turnover']['value']} × "
-              f"{factors['equity_multiplier']['value']} = {None if roe_exact is None else round(roe_exact, 2)}%"
+              f"ROE = {_fmt_val(factors['net_profit_margin']['value'])}% × {_fmt_val(factors['asset_turnover']['value'])} × "
+              f"{_fmt_val(factors['equity_multiplier']['value'])} = {_fmt_val(None if roe_exact is None else round(roe_exact, 2))}%"
               f"（恒等式 {'通过' if identity.get('status') == 'pass' else identity.get('status')}，"
-              f"偏差 {identity.get('diff')} ≤ 容差 {identity.get('tolerance')}）")
+              f"偏差 {_fmt_val(identity.get('diff'))} ≤ 容差 {identity.get('tolerance')}）")
     if cur["basis_fallback"]:
         detail += f"｜⚠️ {cur['basis_fallback_reason']}（basis_fallback=true）"