diff --git a/src/browser/js/Local.zig b/src/browser/js/Local.zig
index 9a09cbcc..e1ec6be3 100644
--- a/src/browser/js/Local.zig
+++ b/src/browser/js/Local.zig
@@ -1488,11 +1488,14 @@ pub fn parseJSON(self: *const Local, json: []const u8) !js.Value {
     };
 }
 
-pub fn throw(self: *const Local, err: []const u8) js.Exception {
-    const handle = self.isolate.createError(err);
+pub fn newException(self: *const Local, ex: anytype) js.Exception {
+    const js_val = self.zigValueToJs(ex, .{}) catch {
+        return .{ .local = self, .handle = self.isolate.createError("internal error") };
+    };
+
     return .{
         .local = self,
-        .handle = handle,
+        .handle = js_val.handle,
     };
 }
 
diff --git a/src/browser/tests/event/abort_controller.html b/src/browser/tests/event/abort_controller.html
index 8d9d8736..b68dcddb 100644
--- a/src/browser/tests/event/abort_controller.html
+++ b/src/browser/tests/event/abort_controller.html
@@ -123,7 +123,8 @@
   const signal = AbortSignal.abort();
 
   testing.expectEqual(true, signal.aborted);
-  testing.expectEqual("AbortError", signal.reason);
+  testing.expectEqual(true, signal.reason instanceof DOMException);
+  testing.expectEqual("AbortError", signal.reason.name);
 }
 </script>
 
@@ -229,7 +230,8 @@
   a1.abort();
   testing.expectEqual(true, s1.aborted)
   testing.expectEqual(s1, target)
-  testing.expectEqual('AbortError', s1.reason)
+  testing.expectEqual(true, s1.reason instanceof DOMException)
+  testing.expectEqual('AbortError', s1.reason.name)
   testing.expectEqual(1, called)
 </script>
 
@@ -237,7 +239,80 @@
   var s2 = AbortSignal.abort('over 9000');
   testing.expectEqual(true, s2.aborted);
   testing.expectEqual('over 9000', s2.reason);
-  testing.expectEqual('AbortError', AbortSignal.abort().reason);
+  testing.expectEqual('AbortError', AbortSignal.abort().reason.name);
+</script>
+
+<script id=abortSignalAnyEmpty>
+{
+  const signal = AbortSignal.any([]);
+  testing.expectEqual(false, signal.aborted);
+}
+</script>
+
+<script id=abortSignalAnyAlreadyAborted>
+{
+  const aborted = AbortSignal.abort("already gone");
+  const c = new AbortController();
+  const signal = AbortSignal.any([c.signal, aborted]);
+
+  testing.expectEqual(true, signal.aborted);
+  testing.expectEqual("already gone", signal.reason);
+}
+</script>
+
+<script id=abortSignalAnyPropagates>
+{
+  const c1 = new AbortController();
+  const c2 = new AbortController();
+  const signal = AbortSignal.any([c1.signal, c2.signal]);
+
+  let eventFired = false;
+  signal.addEventListener('abort', () => {
+    eventFired = true;
+  });
+
+  testing.expectEqual(false, signal.aborted);
+
+  c2.abort("second");
+
+  testing.expectEqual(true, signal.aborted);
+  testing.expectEqual("second", signal.reason);
+  testing.expectEqual(true, eventFired);
+}
+</script>
+
+<script id=abortSignalAnyFirstSourceWins>
+{
+  const c1 = new AbortController();
+  const c2 = new AbortController();
+  const signal = AbortSignal.any([c1.signal, c2.signal]);
+
+  c1.abort("first");
+  c2.abort("second");
+
+  testing.expectEqual(true, signal.aborted);
+  testing.expectEqual("first", signal.reason);
+}
+</script>
+
+<script id=abortSignalAnyTransitive>
+{
+  const c = new AbortController();
+  const mid = AbortSignal.any([c.signal]);
+  const leaf = AbortSignal.any([mid]);
+
+  let leafFired = false;
+  leaf.addEventListener('abort', () => {
+    leafFired = true;
+  });
+
+  c.abort("root");
+
+  testing.expectEqual(true, mid.aborted);
+  testing.expectEqual(true, leaf.aborted);
+  testing.expectEqual("root", leaf.reason);
+  testing.expectEqual(true, leafFired);
+}
 </script>
 
 <script id=abortsignal_timeout type=module>
@@ -250,8 +325,9 @@
 
     await state.done(() => {
       testing.expectEqual(true, s3.aborted);
-      testing.expectEqual('TimeoutError', s3.reason);
-      testing.expectError('Error: TimeoutError', () => {
+      testing.expectEqual(true, s3.reason instanceof DOMException);
+      testing.expectEqual('TimeoutError', s3.reason.name);
+      testing.expectError('TimeoutError: The operation timed out', () => {
         s3.throwIfAborted()
       });
     });
diff --git a/src/browser/webapi/AbortSignal.zig b/src/browser/webapi/AbortSignal.zig
index a1b5cd00..31a3f6a5 100644
--- a/src/browser/webapi/AbortSignal.zig
+++ b/src/browser/webapi/AbortSignal.zig
@@ -23,6 +23,7 @@ const js = @import("../js/js.zig");
 
 const Event = @import("Event.zig");
 const EventTarget = @import("EventTarget.zig");
+const DOMException = @import("DOMException.zig");
 
 const log = lp.log;
 const Execution = js.Execution;
@@ -31,8 +32,11 @@ const AbortSignal = @This();
 
 _proto: *EventTarget,
 _aborted: bool = false,
+_is_dependent: bool = false,
 _reason: Reason = .undefined,
 _on_abort: ?js.Function.Global = null,
+_dependents: std.ArrayList(*AbortSignal) = .{},
+_source_signals: std.ArrayList(*AbortSignal) = .{},
 
 pub fn init(exec: *const Execution) !*AbortSignal {
     return exec._factory.eventTarget(AbortSignal{
@@ -65,19 +69,41 @@ pub fn abort(self: *AbortSignal, reason_: ?Reason, exec: *const Execution) !void
         return;
     }
 
-    self._aborted = true;
+    try self.markAborted(reason_, exec);
 
-    // Store the abort reason (default to a simple string if none provided)
+    // Per spec: mark all direct dependents aborted (with this signal's reason)
+    // BEFORE firing any abort events. The graph is flattened at any() creation,
+    // so we never need to recurse here.
+    var to_dispatch: std.ArrayList(*AbortSignal) = .{};
+    for (self._dependents.items) |dep| {
+        if (dep._aborted) continue;
+        try dep.markAborted(self._reason, exec);
+        try to_dispatch.append(exec.arena, dep);
+    }
+
+    try self.dispatchAbortEvent(exec);
+    for (to_dispatch.items) |dep| {
+        dep.dispatchAbortEvent(exec) catch |err| {
+            log.warn(.app, "abort dependent dispatch", .{ .err = err });
+        };
+    }
+}
+
+fn markAborted(self: *AbortSignal, reason_: ?Reason, exec: *const Execution) !void {
+    self._aborted = true;
     if (reason_) |reason| {
         switch (reason) {
+            .dom => |dom| self._reason = .{ .dom = dom },
             .js_val => |js_val| self._reason = .{ .js_val = js_val },
             .string => |str| self._reason = .{ .string = try exec.dupeString(str) },
             .undefined => self._reason = reason,
         }
     } else {
-        self._reason = .{ .string = "AbortError" };
+        self._reason = .{ .dom = DOMException.fromError(error.AbortError).? };
     }
+}
 
+fn dispatchAbortEvent(self: *AbortSignal, exec: *const Execution) !void {
     const target = self.asEventTarget();
     const on_abort = self._on_abort;
     switch (exec.context.global) {
@@ -97,6 +123,31 @@ pub fn createAborted(reason_: ?js.Value.Global, exec: *const Execution) !*AbortS
     return signal;
 }
 
+pub fn createAny(signals: []const *AbortSignal, exec: *const Execution) !*AbortSignal {
+    const result = try init(exec);
+    for (signals) |source| {
+        if (source._aborted) {
+            try result.abort(source._reason, exec);
+            return result;
+        }
+    }
+
+    result._is_dependent = true;
+
+    for (signals) |source| {
+        if (!source._is_dependent) {
+            try source._dependents.append(exec.arena, result);
+            try result._source_signals.append(exec.arena, source);
+        } else {
+            for (source._source_signals.items) |s| {
+                try s._dependents.append(exec.arena, result);
+                try result._source_signals.append(exec.arena, s);
+            }
+        }
+    }
+    return result;
+}
+
 pub fn createTimeout(delay: u32, exec: *const Execution) !*AbortSignal {
     const callback = try exec.arena.create(TimeoutCallback);
     callback.* = .{
@@ -120,9 +171,10 @@ pub fn throwIfAborted(self: *const AbortSignal, exec: *const Execution) !ThrowIf
 
     if (self._aborted) {
         const exception = switch (self._reason) {
-            .string => |str| local.throw(str),
-            .js_val => |js_val| local.throw(try local.toLocal(js_val).toStringSlice()),
-            .undefined => local.throw("AbortError"),
+            .dom => |err| local.newException(err),
+            .string => |str| local.newException(str),
+            .js_val => |js_val| local.newException(js_val),
+            .undefined => local.newException(DOMException.fromError(error.AbortError).?),
         };
         return .{ .exception = exception };
     }
@@ -131,6 +183,7 @@ pub fn throwIfAborted(self: *const AbortSignal, exec: *const Execution) !ThrowIf
 
 const Reason = union(enum) {
     js_val: js.Value.Global,
+    dom: DOMException,
     string: []const u8,
     undefined: void,
 };
@@ -141,7 +194,7 @@ const TimeoutCallback = struct {
 
     fn run(ctx: *anyopaque) !?u32 {
         const self: *TimeoutCallback = @ptrCast(@alignCast(ctx));
-        self.signal.abort(.{ .string = "TimeoutError" }, self.exec) catch |err| {
+        self.signal.abort(.{ .dom = DOMException.fromError(error.TimeoutError).? }, self.exec) catch |err| {
             log.warn(.app, "abort signal timeout", .{ .err = err });
         };
         return null;
@@ -169,5 +222,6 @@ pub const JsApi = struct {
 
     // Static method
     pub const abort = bridge.function(AbortSignal.createAborted, .{ .static = true });
+    pub const any = bridge.function(AbortSignal.createAny, .{ .static = true });
     pub const timeout = bridge.function(AbortSignal.createTimeout, .{ .static = true });
 };