diff --git a/stdlib/3/concurrent/futures/_base.pyi b/stdlib/3/concurrent/futures/_base.pyi
index 13037d87f..fd0421093 100644
--- a/stdlib/3/concurrent/futures/_base.pyi
+++ b/stdlib/3/concurrent/futures/_base.pyi
@@ -1,21 +1,26 @@
-from typing import TypeVar, Generic, Any, Iterable, Iterator, Callable, Tuple, Optional, Set
+import threading
+from logging import Logger
+from typing import TypeVar, Generic, Any, Iterable, Iterator, Callable, Tuple, Optional, Set, List
 from types import TracebackType
 import sys
 
 FIRST_COMPLETED: str
 FIRST_EXCEPTION: str
 ALL_COMPLETED: str
-PENDING: Any
-RUNNING: Any
-CANCELLED: Any
-CANCELLED_AND_NOTIFIED: Any
-FINISHED: Any
-LOGGER: Any
+PENDING: str
+RUNNING: str
+CANCELLED: str
+CANCELLED_AND_NOTIFIED: str
+FINISHED: str
+LOGGER: Logger
 
 class Error(Exception): ...
 class CancelledError(Error): ...
 class TimeoutError(Error): ...
 
+if sys.version_info >= (3, 7):
+    class BrokenExecutor(RuntimeError): ...
+
 _T = TypeVar('_T')
 
 class Future(Generic[_T]):
@@ -54,3 +59,42 @@ def as_completed(fs: Iterable[Future[_T]], timeout: Optional[float] = ...) -> It
 
 def wait(fs: Iterable[Future[_T]], timeout: Optional[float] = ..., return_when: str = ...) -> Tuple[Set[Future[_T]],
                                                                                                     Set[Future[_T]]]: ...
+
+class _Waiter:
+    event: threading.Event
+    finished_futures: List[Future]
+    def __init__(self) -> None: ...
+    def add_result(self, future: Future) -> None: ...
+    def add_exception(self, future: Future) -> None: ...
+    def add_cancelled(self, future: Future) -> None: ...
+
+
+class _AsCompletedWaiter(_Waiter):
+    lock: threading.Lock
+    def __init__(self) -> None: ...
+    def add_result(self, future: Future) -> None: ...
+    def add_exception(self, future: Future) -> None: ...
+    def add_cancelled(self, future: Future) -> None: ...
+
+
+class _FirstCompletedWaiter(_Waiter):
+    def add_result(self, future: Future) -> None: ...
+    def add_exception(self, future: Future) -> None: ...
+    def add_cancelled(self, future: Future) -> None: ...
+
+
+class _AllCompletedWaiter(_Waiter):
+    num_pending_calls: int
+    stop_on_exception: bool
+    lock: threading.Lock
+    def __init__(self, num_pending_calls: int, stop_on_exception: bool) -> None: ...
+    def add_result(self, future: Future) -> None: ...
+    def add_exception(self, future: Future) -> None: ...
+    def add_cancelled(self, future: Future) -> None: ...
+
+
+class _AcquireFutures:
+    futures: Iterable[Future]
+    def __init__(self, futures: Iterable[Future]) -> None: ...
+    def __enter__(self) -> None: ...
+    def __exit__(self, *args: Any) -> None: ...
diff --git a/stdlib/3/concurrent/futures/thread.pyi b/stdlib/3/concurrent/futures/thread.pyi
index e2b236b8d..c4f895d7a 100644
--- a/stdlib/3/concurrent/futures/thread.pyi
+++ b/stdlib/3/concurrent/futures/thread.pyi
@@ -1,7 +1,13 @@
-from typing import Any, Callable, Optional, Tuple
-from ._base import Executor
+from typing import Any, Callable, Optional, Tuple, TypeVar, Generic
+from ._base import Executor, Future
 import sys
 
+if sys.version_info >= (3, 7):
+    from ._base import BrokenExecutor
+    class BrokenThreadPool(BrokenExecutor): ...
+
+_S = TypeVar('_S')
+
 class ThreadPoolExecutor(Executor):
     if sys.version_info >= (3, 7):
         def __init__(self, max_workers: Optional[int] = ...,
@@ -13,3 +19,13 @@ class ThreadPoolExecutor(Executor):
                      thread_name_prefix: str = ...) -> None: ...
     else:
         def __init__(self, max_workers: Optional[int] = ...) -> None: ...
+
+
+class _WorkItem(Generic[_S]):
+    future: Future
+    fn: Callable[[Future[_S]], Any]
+    args: Any
+    kwargs: Any
+    def __init__(self, future: Future, fn: Callable[[Future[_S]], Any], args: Any,
+                 kwargs: Any) -> None: ...
+    def run(self) -> None: ...
diff --git a/third_party/2/concurrent/futures/_base.pyi b/third_party/2/concurrent/futures/_base.pyi
index 13037d87f..fd0421093 100644
--- a/third_party/2/concurrent/futures/_base.pyi
+++ b/third_party/2/concurrent/futures/_base.pyi
@@ -1,21 +1,26 @@
-from typing import TypeVar, Generic, Any, Iterable, Iterator, Callable, Tuple, Optional, Set
+import threading
+from logging import Logger
+from typing import TypeVar, Generic, Any, Iterable, Iterator, Callable, Tuple, Optional, Set, List
 from types import TracebackType
 import sys
 
 FIRST_COMPLETED: str
 FIRST_EXCEPTION: str
 ALL_COMPLETED: str
-PENDING: Any
-RUNNING: Any
-CANCELLED: Any
-CANCELLED_AND_NOTIFIED: Any
-FINISHED: Any
-LOGGER: Any
+PENDING: str
+RUNNING: str
+CANCELLED: str
+CANCELLED_AND_NOTIFIED: str
+FINISHED: str
+LOGGER: Logger
 
 class Error(Exception): ...
 class CancelledError(Error): ...
 class TimeoutError(Error): ...
 
+if sys.version_info >= (3, 7):
+    class BrokenExecutor(RuntimeError): ...
+
 _T = TypeVar('_T')
 
 class Future(Generic[_T]):
@@ -54,3 +59,42 @@ def as_completed(fs: Iterable[Future[_T]], timeout: Optional[float] = ...) -> It
 
 def wait(fs: Iterable[Future[_T]], timeout: Optional[float] = ..., return_when: str = ...) -> Tuple[Set[Future[_T]],
                                                                                                     Set[Future[_T]]]: ...
+
+class _Waiter:
+    event: threading.Event
+    finished_futures: List[Future]
+    def __init__(self) -> None: ...
+    def add_result(self, future: Future) -> None: ...
+    def add_exception(self, future: Future) -> None: ...
+    def add_cancelled(self, future: Future) -> None: ...
+
+
+class _AsCompletedWaiter(_Waiter):
+    lock: threading.Lock
+    def __init__(self) -> None: ...
+    def add_result(self, future: Future) -> None: ...
+    def add_exception(self, future: Future) -> None: ...
+    def add_cancelled(self, future: Future) -> None: ...
+
+
+class _FirstCompletedWaiter(_Waiter):
+    def add_result(self, future: Future) -> None: ...
+    def add_exception(self, future: Future) -> None: ...
+    def add_cancelled(self, future: Future) -> None: ...
+
+
+class _AllCompletedWaiter(_Waiter):
+    num_pending_calls: int
+    stop_on_exception: bool
+    lock: threading.Lock
+    def __init__(self, num_pending_calls: int, stop_on_exception: bool) -> None: ...
+    def add_result(self, future: Future) -> None: ...
+    def add_exception(self, future: Future) -> None: ...
+    def add_cancelled(self, future: Future) -> None: ...
+
+
+class _AcquireFutures:
+    futures: Iterable[Future]
+    def __init__(self, futures: Iterable[Future]) -> None: ...
+    def __enter__(self) -> None: ...
+    def __exit__(self, *args: Any) -> None: ...
diff --git a/third_party/2/concurrent/futures/thread.pyi b/third_party/2/concurrent/futures/thread.pyi
index e2b236b8d..c4f895d7a 100644
--- a/third_party/2/concurrent/futures/thread.pyi
+++ b/third_party/2/concurrent/futures/thread.pyi
@@ -1,7 +1,13 @@
-from typing import Any, Callable, Optional, Tuple
-from ._base import Executor
+from typing import Any, Callable, Optional, Tuple, TypeVar, Generic
+from ._base import Executor, Future
 import sys
 
+if sys.version_info >= (3, 7):
+    from ._base import BrokenExecutor
+    class BrokenThreadPool(BrokenExecutor): ...
+
+_S = TypeVar('_S')
+
 class ThreadPoolExecutor(Executor):
     if sys.version_info >= (3, 7):
         def __init__(self, max_workers: Optional[int] = ...,
@@ -13,3 +19,13 @@ class ThreadPoolExecutor(Executor):
                      thread_name_prefix: str = ...) -> None: ...
     else:
         def __init__(self, max_workers: Optional[int] = ...) -> None: ...
+
+
+class _WorkItem(Generic[_S]):
+    future: Future
+    fn: Callable[[Future[_S]], Any]
+    args: Any
+    kwargs: Any
+    def __init__(self, future: Future, fn: Callable[[Future[_S]], Any], args: Any,
+                 kwargs: Any) -> None: ...
+    def run(self) -> None: ...