diff --git a/src/cerbero_mcp/exchanges/__init__.py b/src/cerbero_mcp/exchanges/__init__.py
index e69de29..38178c2 100644
--- a/src/cerbero_mcp/exchanges/__init__.py
+++ b/src/cerbero_mcp/exchanges/__init__.py
@@ -0,0 +1,22 @@
+"""Builder centralizzato di client per ClientRegistry."""
+from __future__ import annotations
+
+from typing import Literal
+
+from cerbero_mcp.settings import Settings
+
+Environment = Literal["testnet", "mainnet"]
+
+
+async def build_client(
+    settings: Settings, exchange: str, env: Environment
+):
+    if exchange == "deribit":
+        from cerbero_mcp.exchanges.deribit.client import DeribitClient
+
+        return DeribitClient(
+            client_id=settings.deribit.client_id,
+            client_secret=settings.deribit.client_secret.get_secret_value(),
+            testnet=(env == "testnet"),
+        )
+    raise ValueError(f"unsupported exchange: {exchange}")
diff --git a/tests/unit/test_exchanges_builder.py b/tests/unit/test_exchanges_builder.py
new file mode 100644
index 0000000..0bc1959
--- /dev/null
+++ b/tests/unit/test_exchanges_builder.py
@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_build_client_deribit_returns_correct_url(monkeypatch):
+    from tests.unit.test_settings import _minimal_env
+
+    for k, v in _minimal_env().items():
+        monkeypatch.setenv(k, v)
+
+    from cerbero_mcp.settings import Settings
+    from cerbero_mcp.exchanges import build_client
+
+    s = Settings()
+    c_test = await build_client(s, "deribit", "testnet")
+    c_live = await build_client(s, "deribit", "mainnet")
+
+    # DeribitClient espone base_url come property derivata da self.testnet
+    assert "test" in c_test.base_url.lower()
+    assert "test" not in c_live.base_url.lower()
+
+
+@pytest.mark.asyncio
+async def test_build_client_unknown_exchange_raises(monkeypatch):
+    from tests.unit.test_settings import _minimal_env
+
+    for k, v in _minimal_env().items():
+        monkeypatch.setenv(k, v)
+
+    from cerbero_mcp.settings import Settings
+    from cerbero_mcp.exchanges import build_client
+
+    s = Settings()
+    with pytest.raises(ValueError):
+        await build_client(s, "ftx", "testnet")