diff --git a/stdlib/_typeshed/__init__.pyi b/stdlib/_typeshed/__init__.pyi
index baaa5e3c0..d5e0c691e 100644
--- a/stdlib/_typeshed/__init__.pyi
+++ b/stdlib/_typeshed/__init__.pyi
@@ -64,12 +64,27 @@ class SupportsAllComparisons(SupportsDunderLT, SupportsDunderGT, SupportsDunderL
 SupportsRichComparison: TypeAlias = SupportsDunderLT | SupportsDunderGT
 SupportsRichComparisonT = TypeVar("SupportsRichComparisonT", bound=SupportsRichComparison)  # noqa: Y001
 
+# Dunder protocols
+
+class SupportsAdd(Protocol):
+    def __add__(self, __x: Any) -> Any: ...
+
 class SupportsDivMod(Protocol[_T_contra, _T_co]):
     def __divmod__(self, __other: _T_contra) -> _T_co: ...
 
 class SupportsRDivMod(Protocol[_T_contra, _T_co]):
     def __rdivmod__(self, __other: _T_contra) -> _T_co: ...
 
+# This protocol is generic over the iterator type, while Iterable is
+# generic over the type that is iterated over.
+class SupportsIter(Protocol[_T_co]):
+    def __iter__(self) -> _T_co: ...
+
+# This protocol is generic over the iterator type, while AsyncIterable is
+# generic over the type that is iterated over.
+class SupportsAiter(Protocol[_T_co]):
+    def __aiter__(self) -> _T_co: ...
+
 class SupportsLenAndGetItem(Protocol[_T_co]):
     def __len__(self) -> int: ...
     def __getitem__(self, __k: int) -> _T_co: ...
diff --git a/stdlib/builtins.pyi b/stdlib/builtins.pyi
index 88ec36de5..a5b4ba071 100644
--- a/stdlib/builtins.pyi
+++ b/stdlib/builtins.pyi
@@ -11,8 +11,11 @@ from _typeshed import (
     ReadableBuffer,
     Self,
     StrOrBytesPath,
+    SupportsAdd,
+    SupportsAiter,
     SupportsAnext,
     SupportsDivMod,
+    SupportsIter,
     SupportsKeysAndGetItem,
     SupportsLenAndGetItem,
     SupportsNext,
@@ -71,12 +74,6 @@ _SupportsAnextT = TypeVar("_SupportsAnextT", bound=SupportsAnext[Any], covariant
 _AwaitableT = TypeVar("_AwaitableT", bound=Awaitable[Any])
 _AwaitableT_co = TypeVar("_AwaitableT_co", bound=Awaitable[Any], covariant=True)
 
-class _SupportsIter(Protocol[_T_co]):
-    def __iter__(self) -> _T_co: ...
-
-class _SupportsAiter(Protocol[_T_co]):
-    def __aiter__(self) -> _T_co: ...
-
 class object:
     __doc__: str | None
     __dict__: dict[str, Any]
@@ -1094,7 +1091,7 @@ class _PathLike(Protocol[_AnyStr_co]):
     def __fspath__(self) -> _AnyStr_co: ...
 
 if sys.version_info >= (3, 10):
-    def aiter(__async_iterable: _SupportsAiter[_SupportsAnextT]) -> _SupportsAnextT: ...
+    def aiter(__async_iterable: SupportsAiter[_SupportsAnextT]) -> _SupportsAnextT: ...
 
     class _SupportsSynchronousAnext(Protocol[_AwaitableT_co]):
         def __anext__(self) -> _AwaitableT_co: ...
@@ -1186,7 +1183,7 @@ def hex(__number: int | SupportsIndex) -> str: ...
 def id(__obj: object) -> int: ...
 def input(__prompt: object = ...) -> str: ...
 @overload
-def iter(__iterable: _SupportsIter[_SupportsNextT]) -> _SupportsNextT: ...
+def iter(__iterable: SupportsIter[_SupportsNextT]) -> _SupportsNextT: ...
 @overload
 def iter(__function: Callable[[], _T | None], __sentinel: None) -> Iterator[_T]: ...
 @overload
@@ -1503,11 +1500,8 @@ def sorted(
 @overload
 def sorted(__iterable: Iterable[_T], *, key: Callable[[_T], SupportsRichComparison], reverse: bool = ...) -> list[_T]: ...
 
-class _SupportsSum(Protocol):
-    def __add__(self, __x: Any) -> Any: ...
-
-_SumT = TypeVar("_SumT", bound=_SupportsSum)
-_SumS = TypeVar("_SumS", bound=_SupportsSum)
+_SumT = TypeVar("_SumT", bound=SupportsAdd)
+_SumS = TypeVar("_SumS", bound=SupportsAdd)
 
 @overload
 def sum(__iterable: Iterable[_SumT]) -> _SumT | Literal[0]: ...