diff --git a/src/components/tooltip/NetworkMarker.tsx b/src/components/tooltip/NetworkMarker.tsx
index c7f231c6c3..91c9a4b329 100644
--- a/src/components/tooltip/NetworkMarker.tsx
+++ b/src/components/tooltip/NetworkMarker.tsx
@@ -338,6 +338,22 @@ export function getNetworkMarkerDetails(
     );
   }
 
+  if (payload.secPurpose) {
+    details.push(
+      <TooltipDetail label="Sec-Purpose" key="Network-Sec-Purpose">
+        {payload.secPurpose}
+      </TooltipDetail>
+    );
+  }
+
+  if (payload.deliveryType) {
+    details.push(
+      <TooltipDetail label="Delivery Type" key="Network-Delivery Type">
+        {payload.deliveryType}
+      </TooltipDetail>
+    );
+  }
+
   if (typeof payload.count === 'number') {
     details.push(
       <TooltipDetail label="Requested bytes" key="Network-Requested Bytes">
diff --git a/src/profile-logic/marker-schema.ts b/src/profile-logic/marker-schema.ts
index 59454a280d..5383bdee19 100644
--- a/src/profile-logic/marker-schema.ts
+++ b/src/profile-logic/marker-schema.ts
@@ -83,6 +83,18 @@ export const markerSchemaFrontEndOnly: MarkerSchema[] = [
         label: 'Response Status',
         hidden: true,
       },
+      {
+        format: 'string',
+        key: 'secPurpose',
+        label: 'Sec-Purpose',
+        hidden: true,
+      },
+      {
+        format: 'string',
+        key: 'deliveryType',
+        label: 'Delivery Type',
+        hidden: true,
+      },
     ],
   },
 ];
diff --git a/src/test/components/NetworkChart.test.tsx b/src/test/components/NetworkChart.test.tsx
index df129b0c15..ba71ab9d91 100644
--- a/src/test/components/NetworkChart.test.tsx
+++ b/src/test/components/NetworkChart.test.tsx
@@ -622,6 +622,62 @@ describe('NetworkChartRowBar MIME-type filter', function () {
   });
 });
 
+describe('Network chart prefetch search', function () {
+  // The fields are hidden in the schema, so they never render in the chart;
+  // they exist so a search for "prefetch" narrows to just these requests.
+  function setup() {
+    return setupWithPayload([
+      ...getNetworkMarkers({ uri: 'https://mozilla.org/plain', id: 1 }),
+      ...getNetworkMarkers({
+        uri: 'https://mozilla.org/speculative',
+        id: 2,
+        payload: { secPurpose: 'prefetch' },
+      }),
+      ...getNetworkMarkers({
+        uri: 'https://mozilla.org/activated',
+        id: 3,
+        payload: { deliveryType: 'navigational-prefetch' },
+      }),
+    ]);
+  }
+
+  function visibleUrls(container: HTMLElement) {
+    return Array.from(
+      container.querySelectorAll('.networkChartRowItemLabel')
+    ).map((node) => node.textContent);
+  }
+
+  it('shows every request when not searching', function () {
+    const { container } = setup();
+    expect(visibleUrls(container)).toHaveLength(3);
+  });
+
+  it('narrows to prefetches when searching for "prefetch"', function () {
+    const { container, dispatch } = setup();
+
+    act(() => {
+      dispatch(changeNetworkSearchString('prefetch'));
+    });
+
+    const urls = visibleUrls(container);
+    expect(urls).toHaveLength(2);
+    expect(urls.join(' ')).toContain('/speculative');
+    expect(urls.join(' ')).toContain('/activated');
+  });
+
+  it('narrows to the activated navigation alone', function () {
+    const { container, dispatch } = setup();
+
+    act(() => {
+      dispatch(changeNetworkSearchString('navigational-prefetch'));
+    });
+
+    const urls = visibleUrls(container);
+    expect(urls).toHaveLength(1);
+    expect(urls[0]).toContain('/activated');
+  });
+});
+
 describe('EmptyReasons', () => {
   it("shows a reason when a profile's network markers have been filtered out", () => {
     const { dispatch, container } = setupWithPayload([...NETWORK_MARKERS]);
diff --git a/src/test/components/TooltipMarker.test.tsx b/src/test/components/TooltipMarker.test.tsx
index 938a5bc361..c80c87ae87 100644
--- a/src/test/components/TooltipMarker.test.tsx
+++ b/src/test/components/TooltipMarker.test.tsx
@@ -686,6 +686,30 @@ describe('TooltipMarker', function () {
     expect(container.firstChild).toMatchSnapshot();
   });
 
+  it('renders the Sec-Purpose of a prefetched request', () => {
+    setupWithPayload(
+      getNetworkMarkers({
+        uri: 'https://example.org/next-page.html',
+        payload: { secPurpose: 'prefetch;anonymous-client-ip' },
+      })
+    );
+
+    expect(getValueForProperty('Sec-Purpose')).toBe(
+      'prefetch;anonymous-client-ip'
+    );
+  });
+
+  it('renders the delivery type of a navigation served from a prefetch', () => {
+    setupWithPayload(
+      getNetworkMarkers({
+        uri: 'https://example.org/next-page.html',
+        payload: { deliveryType: 'navigational-prefetch' },
+      })
+    );
+
+    expect(getValueForProperty('Delivery Type')).toBe('navigational-prefetch');
+  });
+
   it('renders the page information for network markers', () => {
     setupWithPayload(
       getNetworkMarkers({
diff --git a/src/types/markers.ts b/src/types/markers.ts
index e3eb9217b5..f60d98dfdd 100644
--- a/src/types/markers.ts
+++ b/src/types/markers.ts
@@ -556,6 +556,15 @@ export type NetworkPayload = {
   // Used to show the HTTP response status code
   responseStatus?: number;
 
+  // The `Sec-Purpose` request header, only present for prefetches.
+  // It's always absent in Firefox < 155.
+  secPurpose?: string;
+
+  // Matches PerformanceNavigationTiming's deliveryType. Only present when the
+  // navigation was served from a prefetch, as "navigational-prefetch".
+  // It's always absent in Firefox < 155.
+  deliveryType?: string;
+
   // NOTE: the following comments are valid for the merged markers. For the raw
   // markers, startTime and endTime have different meanings. Please look
   // `src/profile-logic/marker-data.js` for more information.