diff --git a/src/findata/api/_b3_common.py b/src/findata/api/_b3_common.py
new file mode 100644
index 0000000..564e50d
--- /dev/null
+++ b/src/findata/api/_b3_common.py
@@ -0,0 +1,26 @@
+"""Shared B3 live-quote helpers for the REST and MCP layers.
+
+``yfinance`` is imported lazily so the rest of the API keeps working without
+the optional ``[b3]`` extra installed. Both ``routers/b3.py`` and ``mcp_app.py``
+resolve the quotes module through here, so the install hint lives in one place.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from fastapi import HTTPException
+
+MAX_TICKERS = 20
+
+
+def resolve_quotes() -> Any:
+    """Return the yfinance-backed quotes module, or raise 503 if the extra is missing."""
+    try:
+        from findata.sources.b3 import quotes
+    except ImportError as exc:  # pragma: no cover - only without the [b3] extra
+        raise HTTPException(
+            status_code=503,
+            detail="B3 live quotes need the optional extra: pip install 'openfindata[b3]'",
+        ) from exc
+    return quotes
diff --git a/src/findata/api/mcp_app.py b/src/findata/api/mcp_app.py
index d43a48d..a026e5f 100644
--- a/src/findata/api/mcp_app.py
+++ b/src/findata/api/mcp_app.py
@@ -37,6 +37,7 @@
 from fastapi.responses import JSONResponse
 from pydantic import BaseModel, Field
 
+from findata.api._b3_common import MAX_TICKERS, resolve_quotes
 from findata.registry import lookup
 from findata.sources.anbima import indices as anbima_src
 from findata.sources.aneel import leiloes
@@ -66,7 +67,6 @@
 
 router = APIRouter()
 
-_MAX_TICKERS = 20
 _MIN_YEAR_B3_COTAHIST = 1986  # B3 publishes COTAHIST since 1986
 _RGF_MAX_PERIOD = 3  # RGF quadrimestre runs 1..3
 
@@ -384,16 +384,6 @@ async def cvm_structured_fund(
 # ── B3: Bolsa ─────────────────────────────────────────────────────
 
 
-def _b3_quotes() -> Any:
-    try:
-        from findata.sources.b3 import quotes
-    except ImportError as exc:  # pragma: no cover, only without the [b3] extra
-        raise HTTPException(
-            503, "Live quotes need the optional extra: pip install 'openfindata[b3]'"
-        ) from exc
-    return quotes
-
-
 @router.get(
     "/b3/quote",
     operation_id="b3_quote",
@@ -408,12 +398,12 @@ async def b3_quote(
     """Current quote(s) from the optional yfinance-backed source. For canonical,
     official end-of-day history use ``b3_cotahist`` instead.
     """
-    quotes = _b3_quotes()
+    quotes = resolve_quotes()
     ticker_list = [t.strip() for t in tickers.split(",") if t.strip()]
     if not ticker_list:
         raise HTTPException(400, "at least one ticker is required")
-    if len(ticker_list) > _MAX_TICKERS:
-        raise HTTPException(400, f"max {_MAX_TICKERS} tickers per request")
+    if len(ticker_list) > MAX_TICKERS:
+        raise HTTPException(400, f"max {MAX_TICKERS} tickers per request")
     if len(ticker_list) == 1:
         return await quotes.get_quote(ticker_list[0])
     return await quotes.get_multiple_quotes(ticker_list)
@@ -655,11 +645,7 @@ async def anbima_tool(
     if dataset == "ettj":
         return await anbima_src.get_ettj(data)
     if dataset == "debentures":
-        rows = await anbima_src.get_debentures(data)
-        if emissor:
-            needle = emissor.upper()
-            rows = [r for r in rows if needle in r.emissor.upper()]
-        return rows[:limit]
+        return (await anbima_src.get_debentures(data, emissor=emissor))[:limit]
     fam = anbima_src.IMAFamily(family) if family else None
     return (await anbima_src.get_ima(fam))[:limit]
 
diff --git a/src/findata/api/routers/anbima.py b/src/findata/api/routers/anbima.py
index a92346c..6af0e87 100644
--- a/src/findata/api/routers/anbima.py
+++ b/src/findata/api/routers/anbima.py
@@ -41,10 +41,7 @@ async def debentures(
     limit: int = Query(default=500, ge=1, le=5000),
 ) -> list[anbima.DebentureQuote]:
     """Daily secondary-market quotes for outstanding debentures."""
-    rows = await anbima.get_debentures(data)
-    if emissor:
-        needle = emissor.upper()
-        rows = [r for r in rows if needle in r.emissor.upper()]
+    rows = await anbima.get_debentures(data, emissor=emissor)
     return rows[:limit]
 
 
diff --git a/src/findata/api/routers/b3.py b/src/findata/api/routers/b3.py
index 41d0ffc..48a1f96 100644
--- a/src/findata/api/routers/b3.py
+++ b/src/findata/api/routers/b3.py
@@ -12,29 +12,18 @@
 
 from fastapi import APIRouter, HTTPException, Path, Query
 
+from findata.api._b3_common import MAX_TICKERS, resolve_quotes
 from findata.sources.b3 import cotahist, indices
 
 router = APIRouter(prefix="/b3", tags=["B3 - Bolsa"])
 
-_MAX_TICKERS_PER_REQUEST = 20
 _CURRENT_YEAR = date.today().year
 
 
-def _quotes() -> Any:
-    try:
-        from findata.sources.b3 import quotes
-    except ImportError as exc:  # pragma: no cover — triggered only without yfinance
-        raise HTTPException(
-            status_code=503,
-            detail=("B3 support is disabled. Install with: pip install 'openfindata[b3]'"),
-        ) from exc
-    return quotes
-
-
 @router.get("/quote/{ticker}")
 async def get_quote(ticker: str) -> Any:
     """Get current stock quote for a B3 ticker (e.g., PETR4, VALE3, WEGE3)."""
-    quotes = _quotes()
+    quotes = resolve_quotes()
     try:
         return await quotes.get_quote(ticker)
     except HTTPException:
@@ -56,7 +45,7 @@ async def get_history(
     ),
 ) -> Any:
     """Get historical price data for a B3 stock."""
-    quotes = _quotes()
+    quotes = resolve_quotes()
     try:
         return await quotes.get_history(ticker, period, interval)
     except HTTPException:
@@ -70,14 +59,14 @@ async def get_multiple_quotes(
     tickers: str = Query(..., description="Comma-separated tickers (e.g., PETR4,VALE3,ITUB4)"),
 ) -> Any:
     """Get current quotes for multiple B3 tickers."""
-    quotes = _quotes()
+    quotes = resolve_quotes()
     ticker_list = [t.strip() for t in tickers.split(",") if t.strip()]
     if not ticker_list:
         raise HTTPException(status_code=400, detail="At least one ticker is required")
-    if len(ticker_list) > _MAX_TICKERS_PER_REQUEST:
+    if len(ticker_list) > MAX_TICKERS:
         raise HTTPException(
             status_code=400,
-            detail=f"Max {_MAX_TICKERS_PER_REQUEST} tickers per request",
+            detail=f"Max {MAX_TICKERS} tickers per request",
         )
     try:
         return await quotes.get_multiple_quotes(ticker_list)
diff --git a/src/findata/sources/anbima/indices.py b/src/findata/sources/anbima/indices.py
index 0682303..1c8c527 100644
--- a/src/findata/sources/anbima/indices.py
+++ b/src/findata/sources/anbima/indices.py
@@ -555,7 +555,9 @@ async def _fetch_anbima_txt(url: str, label: str, d: date) -> str | None:
 # ── Debêntures (daily TXT) ───────────────────────────────────────
 
 
-async def get_debentures(data_referencia: date | None = None) -> list[DebentureQuote]:
+async def get_debentures(
+    data_referencia: date | None = None, emissor: str | None = None
+) -> list[DebentureQuote]:
     """Daily secondary-market quotes for outstanding debentures."""
     d = data_referencia or date.today()
     ymd = d.strftime("%y%m%d")
@@ -597,6 +599,9 @@ async def get_debentures(data_referencia: date | None = None) -> list[DebentureQ
         )
     if not header_seen:
         logger.warning("debentures file for %s had no recognisable header row", d)
+    if emissor:
+        needle = emissor.upper()
+        rows = [r for r in rows if needle in r.emissor.upper()]
     return rows