diff --git a/x-pack/plugins/stack_alerts/server/alert_types/index_threshold/alert_type.test.ts b/x-pack/plugins/stack_alerts/server/alert_types/index_threshold/alert_type.test.ts
index 6584852babd16..fb9754edae6f1 100644
--- a/x-pack/plugins/stack_alerts/server/alert_types/index_threshold/alert_type.test.ts
+++ b/x-pack/plugins/stack_alerts/server/alert_types/index_threshold/alert_type.test.ts
@@ -5,19 +5,28 @@
  * 2.0.
  */
 
+import uuid from 'uuid';
 import type { Writable } from '@kbn/utility-types';
 import { loggingSystemMock } from '../../../../../../src/core/server/mocks';
-import { getAlertType } from './alert_type';
+import { AlertServices } from '../../../../alerting/server';
+import { getAlertType, ActionGroupId } from './alert_type';
+import { ActionContext } from './action_context';
 import { Params } from './alert_type_params';
+import { AlertServicesMock, alertsMock } from '../../../../alerting/server/mocks';
 
 describe('alertType', () => {
   const logger = loggingSystemMock.create().get();
   const data = {
     timeSeriesQuery: jest.fn(),
   };
+  const alertServices: AlertServicesMock = alertsMock.createAlertServices();
 
   const alertType = getAlertType(logger, Promise.resolve(data));
 
+  afterEach(() => {
+    data.timeSeriesQuery.mockReset();
+  });
+
   it('alert type creation structure is the expected value', async () => {
     expect(alertType.id).toBe('.index-threshold');
     expect(alertType.name).toBe('Index threshold');
@@ -135,4 +144,198 @@ describe('alertType', () => {
       `"[aggType]: invalid aggType: \\"foo\\""`
     );
   });
+
+  it('should ensure 0 results fires actions if it passes the comparator check', async () => {
+    data.timeSeriesQuery.mockImplementation((...args) => {
+      return {
+        results: [
+          {
+            group: 'all documents',
+            metrics: [['2021-07-14T14:49:30.978Z', 0]],
+          },
+        ],
+      };
+    });
+    const params: Params = {
+      index: 'index-name',
+      timeField: 'time-field',
+      aggType: 'foo',
+      groupBy: 'all',
+      timeWindowSize: 5,
+      timeWindowUnit: 'm',
+      thresholdComparator: '<',
+      threshold: [1],
+    };
+
+    await alertType.executor({
+      alertId: uuid.v4(),
+      startedAt: new Date(),
+      previousStartedAt: new Date(),
+      services: (alertServices as unknown) as AlertServices<
+        {},
+        ActionContext,
+        typeof ActionGroupId
+      >,
+      params,
+      state: {
+        latestTimestamp: undefined,
+      },
+      spaceId: uuid.v4(),
+      name: uuid.v4(),
+      tags: [],
+      createdBy: null,
+      updatedBy: null,
+      rule: {
+        name: uuid.v4(),
+        tags: [],
+        consumer: '',
+        producer: '',
+        ruleTypeId: '',
+        ruleTypeName: '',
+        enabled: true,
+        schedule: {
+          interval: '1h',
+        },
+        actions: [],
+        createdBy: null,
+        updatedBy: null,
+        createdAt: new Date(),
+        updatedAt: new Date(),
+        throttle: null,
+        notifyWhen: null,
+      },
+    });
+
+    expect(alertServices.alertInstanceFactory).toHaveBeenCalledWith('all documents');
+  });
+
+  it('should ensure a null result does not fire actions', async () => {
+    const customAlertServices: AlertServicesMock = alertsMock.createAlertServices();
+    data.timeSeriesQuery.mockImplementation((...args) => {
+      return {
+        results: [
+          {
+            group: 'all documents',
+            metrics: [['2021-07-14T14:49:30.978Z', null]],
+          },
+        ],
+      };
+    });
+    const params: Params = {
+      index: 'index-name',
+      timeField: 'time-field',
+      aggType: 'foo',
+      groupBy: 'all',
+      timeWindowSize: 5,
+      timeWindowUnit: 'm',
+      thresholdComparator: '<',
+      threshold: [1],
+    };
+
+    await alertType.executor({
+      alertId: uuid.v4(),
+      startedAt: new Date(),
+      previousStartedAt: new Date(),
+      services: (customAlertServices as unknown) as AlertServices<
+        {},
+        ActionContext,
+        typeof ActionGroupId
+      >,
+      params,
+      state: {
+        latestTimestamp: undefined,
+      },
+      spaceId: uuid.v4(),
+      name: uuid.v4(),
+      tags: [],
+      createdBy: null,
+      updatedBy: null,
+      rule: {
+        name: uuid.v4(),
+        tags: [],
+        consumer: '',
+        producer: '',
+        ruleTypeId: '',
+        ruleTypeName: '',
+        enabled: true,
+        schedule: {
+          interval: '1h',
+        },
+        actions: [],
+        createdBy: null,
+        updatedBy: null,
+        createdAt: new Date(),
+        updatedAt: new Date(),
+        throttle: null,
+        notifyWhen: null,
+      },
+    });
+
+    expect(customAlertServices.alertInstanceFactory).not.toHaveBeenCalled();
+  });
+
+  it('should ensure an undefined result does not fire actions', async () => {
+    const customAlertServices: AlertServicesMock = alertsMock.createAlertServices();
+    data.timeSeriesQuery.mockImplementation((...args) => {
+      return {
+        results: [
+          {
+            group: 'all documents',
+            metrics: [['2021-07-14T14:49:30.978Z', undefined]],
+          },
+        ],
+      };
+    });
+    const params: Params = {
+      index: 'index-name',
+      timeField: 'time-field',
+      aggType: 'foo',
+      groupBy: 'all',
+      timeWindowSize: 5,
+      timeWindowUnit: 'm',
+      thresholdComparator: '<',
+      threshold: [1],
+    };
+
+    await alertType.executor({
+      alertId: uuid.v4(),
+      startedAt: new Date(),
+      previousStartedAt: new Date(),
+      services: (customAlertServices as unknown) as AlertServices<
+        {},
+        ActionContext,
+        typeof ActionGroupId
+      >,
+      params,
+      state: {
+        latestTimestamp: undefined,
+      },
+      spaceId: uuid.v4(),
+      name: uuid.v4(),
+      tags: [],
+      createdBy: null,
+      updatedBy: null,
+      rule: {
+        name: uuid.v4(),
+        tags: [],
+        consumer: '',
+        producer: '',
+        ruleTypeId: '',
+        ruleTypeName: '',
+        enabled: true,
+        schedule: {
+          interval: '1h',
+        },
+        actions: [],
+        createdBy: null,
+        updatedBy: null,
+        createdAt: new Date(),
+        updatedAt: new Date(),
+        throttle: null,
+        notifyWhen: null,
+      },
+    });
+
+    expect(customAlertServices.alertInstanceFactory).not.toHaveBeenCalled();
+  });
 });
diff --git a/x-pack/plugins/stack_alerts/server/alert_types/index_threshold/alert_type.ts b/x-pack/plugins/stack_alerts/server/alert_types/index_threshold/alert_type.ts
index c9b2696d6b228..46c3c3467cefe 100644
--- a/x-pack/plugins/stack_alerts/server/alert_types/index_threshold/alert_type.ts
+++ b/x-pack/plugins/stack_alerts/server/alert_types/index_threshold/alert_type.ts
@@ -18,7 +18,7 @@ import {
 import { ComparatorFns, getHumanReadableComparator } from '../lib';
 
 export const ID = '.index-threshold';
-const ActionGroupId = 'threshold met';
+export const ActionGroupId = 'threshold met';
 
 export function getAlertType(
   logger: Logger,
@@ -180,7 +180,7 @@ export function getAlertType(
         groupResult.metrics && groupResult.metrics.length > 0 ? groupResult.metrics[0] : null;
       const value = metric && metric.length === 2 ? metric[1] : null;
 
-      if (!value) {
+      if (value === null || value === undefined) {
         logger.debug(
           `alert ${ID}:${alertId} "${name}": no metrics found for group ${instanceId}} from groupResult ${JSON.stringify(
             groupResult