diff --git a/litellm/litellm_core_utils/ptu_pricing.py b/litellm/litellm_core_utils/ptu_pricing.py
index f9a4335bb4c..683ef9a5ba4 100644
--- a/litellm/litellm_core_utils/ptu_pricing.py
+++ b/litellm/litellm_core_utils/ptu_pricing.py
@@ -229,8 +229,11 @@ def ptu_config_error(model_info: Mapping[str, object], *, model_name: str | None
 
     has_count: Final = model_info.get("ptu_count") is not None
     has_rate: Final = model_info.get("cost_per_ptu_per_hour") is not None
-    if not has_count and not has_rate:
+    has_shares: Final = model_info.get("ptu_shares") is not None
+    if not has_count and not has_rate and not has_shares:
         return None
+    if not has_count and not has_rate:
+        return _named("ptu_count and cost_per_ptu_per_hour are required when ptu_shares is set", model_name)
     if has_count != has_rate:
         return _named("ptu_count and cost_per_ptu_per_hour must be set together", model_name)
     if effective_from is None:
diff --git a/tests/unit/litellm_core_utils/test_ptu_pricing.py b/tests/unit/litellm_core_utils/test_ptu_pricing.py
index 7dda3432e43..28b57fb328d 100644
--- a/tests/unit/litellm_core_utils/test_ptu_pricing.py
+++ b/tests/unit/litellm_core_utils/test_ptu_pricing.py
@@ -439,6 +439,21 @@ def test_a_fractional_count_reserves_nothing():
     assert ptu_terms({**_SHARED, "ptu_count": 100.5}) is None
 
 
+@pytest.mark.parametrize(
+    "shares_only",
+    [
+        {"ptu_shares": {"team-a": 60, "team-b": 40}},
+        {"ptu_shares": {"team-a": 60, "team-b": 40}, "ptu_effective_from": "2026-01-01T00:00:00Z"},
+    ],
+    ids=["shares alone", "shares with a window"],
+)
+def test_shares_without_the_count_and_rate_are_refused_instead_of_registering_unpriced(shares_only):
+    """Shares split a count, so a split with no count has nothing to add up to and would register a
+    deployment the share filter and ceiling honour while flat cost never rolls up."""
+    assert ptu_config_error(shares_only) == "ptu_count and cost_per_ptu_per_hour are required when ptu_shares is set"
+    assert ptu_terms(shares_only) is None
+
+
 def test_the_split_is_named_after_the_deployment_when_the_caller_supplies_one():
     error = ptu_config_error({**_SHARED, "ptu_shares": {"team-a": 1}}, model_name="gpt-4.1-ptu")
 
diff --git a/tests/unit/proxy/management_endpoints/test_ptu_model_settings.py b/tests/unit/proxy/management_endpoints/test_ptu_model_settings.py
index ce2e865d69d..8bbde32e756 100644
--- a/tests/unit/proxy/management_endpoints/test_ptu_model_settings.py
+++ b/tests/unit/proxy/management_endpoints/test_ptu_model_settings.py
@@ -1334,6 +1334,13 @@ def test_validate_helper_refuses_shares_that_do_not_add_up_to_the_count():
     assert "4 of 5 allocated" in exc.value.detail
 
 
+def test_validate_helper_refuses_shares_declared_without_a_count_and_rate():
+    with pytest.raises(HTTPException) as exc:
+        _validate_ptu_model_info({"ptu_shares": {"team-a": 3, "team-b": 2}, "ptu_effective_from": _SHARED_START})
+    assert exc.value.status_code == 400
+    assert exc.value.detail == "ptu_count and cost_per_ptu_per_hour are required when ptu_shares is set"
+
+
 class _TeamLookup:
     def __init__(self, existing: frozenset[str]) -> None:
         self.existing: Final = existing