diff --git a/api/libs/handlers/src/metrics/sharing/mod.rs b/api/libs/handlers/src/metrics/sharing/mod.rs
index 1a8419a57..f9b313bb4 100644
--- a/api/libs/handlers/src/metrics/sharing/mod.rs
+++ b/api/libs/handlers/src/metrics/sharing/mod.rs
@@ -1,7 +1,9 @@
 pub mod list_sharing_handler;
 pub mod create_sharing_handler;
 pub mod delete_sharing_handler;
+pub mod update_sharing_handler;
 
 pub use list_sharing_handler::*;
 pub use create_sharing_handler::*;
 pub use delete_sharing_handler::*;
+pub use update_sharing_handler::*;
diff --git a/api/libs/handlers/src/metrics/sharing/update_sharing_handler.rs b/api/libs/handlers/src/metrics/sharing/update_sharing_handler.rs
new file mode 100644
index 000000000..29e33d990
--- /dev/null
+++ b/api/libs/handlers/src/metrics/sharing/update_sharing_handler.rs
@@ -0,0 +1,102 @@
+use anyhow::{anyhow, Result};
+use database::{
+    enums::{AssetPermissionRole, AssetType, IdentityType},
+    helpers::metric_files::fetch_metric_file,
+};
+use sharing::{
+    check_asset_permission::has_permission,
+    create_asset_permission::create_share_by_email,
+};
+use tracing::info;
+use uuid::Uuid;
+
+/// Handler to update sharing permissions for a metric
+///
+/// # Arguments
+/// * `metric_id` - The UUID of the metric to update sharing permissions for
+/// * `user_id` - The UUID of the user making the request
+/// * `emails_and_roles` - List of tuples containing (email, role) pairs to update
+///
+/// # Returns
+/// * `Result<()>` - Success if all sharing permissions were updated
+pub async fn update_metric_sharing_handler(
+    metric_id: &Uuid,
+    user_id: &Uuid,
+    emails_and_roles: Vec<(String, AssetPermissionRole)>,
+) -> Result<()> {
+    info!(
+        metric_id = %metric_id,
+        user_id = %user_id,
+        recipients_count = emails_and_roles.len(),
+        "Updating sharing permissions for metric"
+    );
+
+    // 1. Validate the metric exists
+    let _metric = match fetch_metric_file(metric_id).await? {
+        Some(metric) => metric,
+        None => return Err(anyhow!("Metric not found")),
+    };
+
+    // 2. Check if user has permission to update sharing for the metric (Owner or FullAccess)
+    let has_permission = has_permission(
+        *metric_id,
+        AssetType::MetricFile,
+        *user_id,
+        IdentityType::User,
+        AssetPermissionRole::FullAccess, // Owner role implicitly has FullAccess permissions
+    ).await?;
+
+    if !has_permission {
+        return Err(anyhow!("User does not have permission to update sharing for this metric"));
+    }
+
+    // 3. Process each email-role pair and update sharing permissions
+    for (email, role) in emails_and_roles {
+        // Validate email format
+        if !email.contains('@') {
+            return Err(anyhow!("Invalid email format: {}", email));
+        }
+
+        // Update (or create if not exists) the permission using create_share_by_email
+        // The create_share_by_email function handles both creation and updates with upsert
+        match create_share_by_email(
+            &email,
+            *metric_id,
+            AssetType::MetricFile,
+            role,
+            *user_id,
+        ).await {
+            Ok(_) => {
+                info!("Updated sharing permission for email: {} with role: {:?} on metric: {}", email, role, metric_id);
+            },
+            Err(e) => {
+                return Err(anyhow!("Failed to update sharing for email {}: {}", email, e));
+            }
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn test_update_metric_sharing_invalid_email() {
+        let metric_id = Uuid::new_v4();
+        let user_id = Uuid::new_v4();
+        let emails_and_roles = vec![("invalid-email-format".to_string(), AssetPermissionRole::CanView)];
+
+        let result = update_metric_sharing_handler(&metric_id, &user_id, emails_and_roles).await;
+
+        assert!(result.is_err());
+        let error = result.unwrap_err().to_string();
+        assert!(error.contains("Invalid email format"));
+    }
+
+    // Note: For comprehensive tests, we would need to set up proper mocks
+    // for external dependencies like fetch_metric_file, has_permission,
+    // and create_share_by_email. This would typically involve using a
+    // mocking framework that's compatible with async functions.
+}
\ No newline at end of file
diff --git a/api/prds/active/api_metrics_sharing_summary.md b/api/prds/active/api_metrics_sharing_summary.md
index e9e91dfb8..0bf83dd1d 100644
--- a/api/prds/active/api_metrics_sharing_summary.md
+++ b/api/prds/active/api_metrics_sharing_summary.md
@@ -16,8 +16,8 @@ The implementation is broken down into the following components, each with its o
 2. **Create Metrics Sharing Endpoint** - POST /metrics/:id/sharing
    - PRD: [api_metrics_sharing_create.md](/Users/dallin/buster/buster/api/prds/active/api_metrics_sharing_create.md)
 
-3. **Update Metrics Sharing Endpoint** - PUT /metrics/:id/sharing
-   - PRD: [api_metrics_sharing_update.md](/Users/dallin/buster/buster/api/prds/active/api_metrics_sharing_update.md)
+3. **Update Metrics Sharing Endpoint** - PUT /metrics/:id/sharing ✅
+   - PRD: [api_metrics_sharing_update.md](/Users/dallin/api_metrics_sharing_update/api/prds/active/api_metrics_sharing_update.md)
 
 4. **Delete Metrics Sharing Endpoint** - DELETE /metrics/:id/sharing
    - PRD: [api_metrics_sharing_delete.md](/Users/dallin/buster/buster/api/prds/active/api_metrics_sharing_delete.md)
@@ -68,7 +68,7 @@ After Phase 1 is complete, the following components can be implemented in parall
   - Uses `create_share_by_email` from `@[api/libs/sharing/src]/create_asset_permission.rs`
   - Uses `has_permission` from `@[api/libs/sharing/src]/check_asset_permission.rs`
 
-- **Update Sharing Endpoint**
+- **Update Sharing Endpoint** ✅
   - Uses `create_share_by_email` from `@[api/libs/sharing/src]/create_asset_permission.rs`
   - Uses `has_permission` from `@[api/libs/sharing/src]/check_asset_permission.rs`
 
diff --git a/api/prds/active/api_metrics_sharing_update.md b/api/prds/active/api_metrics_sharing_update.md
index 3c284b571..26f184ea7 100644
--- a/api/prds/active/api_metrics_sharing_update.md
+++ b/api/prds/active/api_metrics_sharing_update.md
@@ -1,4 +1,5 @@
 # API Metrics Sharing - Update Endpoint PRD
+✅ Implemented
 
 ## Problem Statement
 Users need the ability to update sharing permissions for metrics through a REST API endpoint.
diff --git a/api/src/routes/rest/routes/collections/sharing/list_sharing.rs b/api/src/routes/rest/routes/collections/sharing/list_sharing.rs
index 26335688f..58aae0275 100644
--- a/api/src/routes/rest/routes/collections/sharing/list_sharing.rs
+++ b/api/src/routes/rest/routes/collections/sharing/list_sharing.rs
@@ -44,7 +44,7 @@ pub async fn list_collection_sharing_rest_handler(
                     role: p.permission.role,
                 }).collect(),
             };
-            Ok(ApiResponse::Success(response))
+            Ok(ApiResponse::JsonData(response))
         },
         Err(e) => {
             tracing::error!("Error listing sharing permissions: {}", e);
diff --git a/api/src/routes/rest/routes/metrics/sharing/mod.rs b/api/src/routes/rest/routes/metrics/sharing/mod.rs
index f57767361..e90679c76 100644
--- a/api/src/routes/rest/routes/metrics/sharing/mod.rs
+++ b/api/src/routes/rest/routes/metrics/sharing/mod.rs
@@ -1,15 +1,17 @@
 use axum::{
-    routing::{get, post, delete},
+    routing::{get, post, delete, put},
     Router,
 };
 
 mod list_sharing;
 mod create_sharing;
 mod delete_sharing;
+mod update_sharing;
 
 pub fn router() -> Router {
     Router::new()
         .route("/", get(list_sharing::list_metric_sharing_rest_handler))
         .route("/", post(create_sharing::create_metric_sharing_rest_handler))
+        .route("/", put(update_sharing::update_metric_sharing_rest_handler))
         .route("/", delete(delete_sharing::delete_metric_sharing_rest_handler))
 }
\ No newline at end of file
diff --git a/api/src/routes/rest/routes/metrics/sharing/update_sharing.rs b/api/src/routes/rest/routes/metrics/sharing/update_sharing.rs
new file mode 100644
index 000000000..55207257a
--- /dev/null
+++ b/api/src/routes/rest/routes/metrics/sharing/update_sharing.rs
@@ -0,0 +1,65 @@
+use axum::{
+    extract::{Json, Path},
+    http::StatusCode,
+    Extension,
+};
+use database::enums::AssetPermissionRole;
+use handlers::metrics::sharing::update_metric_sharing_handler;
+use middleware::AuthenticatedUser;
+use serde::Deserialize;
+use uuid::Uuid;
+
+use crate::routes::rest::ApiResponse;
+
+/// Structure for a single share recipient with their role
+#[derive(Debug, Deserialize)]
+pub struct ShareRecipient {
+    pub email: String,
+    pub role: AssetPermissionRole,
+}
+
+/// REST handler for updating sharing permissions for a metric
+pub async fn update_metric_sharing_rest_handler(
+    Extension(user): Extension<AuthenticatedUser>,
+    Path(id): Path<Uuid>,
+    Json(request): Json<Vec<ShareRecipient>>,
+) -> Result<ApiResponse<String>, (StatusCode, String)> {
+    tracing::info!(
+        "Processing PUT request for metric sharing with ID: {}, user_id: {}",
+        id,
+        user.id
+    );
+
+    let emails_and_roles: Vec<(String, AssetPermissionRole)> = request
+        .into_iter()
+        .map(|recipient| (recipient.email, recipient.role))
+        .collect();
+
+    match update_metric_sharing_handler(&id, &user.id, emails_and_roles).await {
+        Ok(_) => Ok(ApiResponse::JsonData(
+            "Sharing permissions updated successfully".to_string(),
+        )),
+        Err(e) => {
+            tracing::error!("Error updating sharing permissions: {}", e);
+
+            // Map specific errors to appropriate status codes
+            let error_message = e.to_string();
+
+            if error_message.contains("not found") {
+                return Err((StatusCode::NOT_FOUND, format!("Metric not found: {}", e)));
+            } else if error_message.contains("permission") {
+                return Err((
+                    StatusCode::FORBIDDEN,
+                    format!("Insufficient permissions: {}", e),
+                ));
+            } else if error_message.contains("Invalid email") {
+                return Err((StatusCode::BAD_REQUEST, format!("Invalid email: {}", e)));
+            }
+
+            Err((
+                StatusCode::INTERNAL_SERVER_ERROR,
+                format!("Failed to update sharing permissions: {}", e),
+            ))
+        }
+    }
+}
\ No newline at end of file
diff --git a/api/tests/integration/metrics/sharing/mod.rs b/api/tests/integration/metrics/sharing/mod.rs
index 59e5bac50..bd317d6e2 100644
--- a/api/tests/integration/metrics/sharing/mod.rs
+++ b/api/tests/integration/metrics/sharing/mod.rs
@@ -1,3 +1,4 @@
 pub mod list_sharing_test;
 pub mod create_sharing_test;
 pub mod delete_sharing_test;
+pub mod update_sharing_test;
diff --git a/api/tests/integration/metrics/sharing/update_sharing_test.rs b/api/tests/integration/metrics/sharing/update_sharing_test.rs
new file mode 100644
index 000000000..095de3111
--- /dev/null
+++ b/api/tests/integration/metrics/sharing/update_sharing_test.rs
@@ -0,0 +1,317 @@
+use axum::http::StatusCode;
+use chrono::Utc;
+use database::{
+    enums::{AssetPermissionRole, AssetType, IdentityType},
+    models::{AssetPermission},
+    pool::get_pg_pool,
+    schema::{users, metric_files, asset_permissions},
+};
+use diesel::{ExpressionMethods, QueryDsl};
+use diesel_async::RunQueryDsl;
+use serde_json::json;
+use uuid::Uuid;
+
+use crate::common::{
+    http::client::TestClient,
+    fixtures::{users::create_test_user, metrics::create_test_metric_file},
+};
+
+#[tokio::test]
+async fn test_update_metric_sharing_success() {
+    // Setup test database connection
+    let mut conn = get_pg_pool().get().await.unwrap();
+    
+    // 1. Create test owner and shared user
+    let owner = create_test_user("owner@example.com");
+    let org_id = Uuid::new_v4(); // Need org id for fixture
+    diesel::insert_into(users::table)
+        .values(&owner)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+        
+    let shared_user = create_test_user("shared@example.com");
+    diesel::insert_into(users::table)
+        .values(&shared_user)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 2. Create test metric
+    let metric = create_test_metric_file(&owner.id, &org_id, None);
+    diesel::insert_into(metric_files::table)
+        .values(&metric)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 3. Create owner permission for test user
+    let now = Utc::now();
+    let owner_permission = AssetPermission {
+        identity_id: owner.id,
+        identity_type: IdentityType::User,
+        asset_id: metric.id,
+        asset_type: AssetType::MetricFile,
+        role: AssetPermissionRole::Owner,
+        created_at: now,
+        updated_at: now,
+        deleted_at: None,
+        created_by: owner.id,
+        updated_by: owner.id,
+    };
+    
+    // 4. Create existing CanView permission for shared user
+    let shared_permission = AssetPermission {
+        identity_id: shared_user.id,
+        identity_type: IdentityType::User,
+        asset_id: metric.id,
+        asset_type: AssetType::MetricFile,
+        role: AssetPermissionRole::CanView,
+        created_at: now,
+        updated_at: now,
+        deleted_at: None,
+        created_by: owner.id,
+        updated_by: owner.id,
+    };
+    
+    // Insert both permissions
+    diesel::insert_into(asset_permissions::table)
+        .values(&vec![owner_permission, shared_permission])
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 5. Create test client
+    let client = TestClient::new().await;
+    
+    // 6. Send update sharing request to change role from CanView to CanEdit
+    let response = client
+        .put(&format!("/metrics/{}/sharing", metric.id))
+        .with_auth(&owner.id.to_string())
+        .json(&json!([
+            {
+                "email": "shared@example.com",
+                "role": "CanEdit"
+            }
+        ]))
+        .send()
+        .await;
+    
+    // 7. Assert response
+    assert_eq!(response.status(), StatusCode::OK);
+    
+    // 8. Check that permission was updated
+    let permissions = asset_permissions::table
+        .filter(asset_permissions::asset_id.eq(metric.id))
+        .filter(asset_permissions::identity_id.eq(shared_user.id))
+        .filter(asset_permissions::asset_type.eq(AssetType::MetricFile))
+        .filter(asset_permissions::identity_type.eq(IdentityType::User))
+        .filter(asset_permissions::deleted_at.is_null())
+        .load::<AssetPermission>(&mut conn)
+        .await
+        .unwrap();
+    
+    assert_eq!(permissions.len(), 1);
+    assert_eq!(permissions[0].role, AssetPermissionRole::CanEdit); // Role should be updated
+}
+
+#[tokio::test]
+async fn test_update_metric_sharing_unauthorized() {
+    // Setup test database connection
+    let mut conn = get_pg_pool().get().await.unwrap();
+    
+    // 1. Create test owner, shared user, and unauthorized user
+    let owner = create_test_user("owner@example.com");
+    let org_id = Uuid::new_v4();
+    diesel::insert_into(users::table)
+        .values(&owner)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+        
+    let shared_user = create_test_user("shared@example.com");
+    diesel::insert_into(users::table)
+        .values(&shared_user)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    let unauthorized_user = create_test_user("unauthorized@example.com");
+    diesel::insert_into(users::table)
+        .values(&unauthorized_user)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 2. Create test metric
+    let metric = create_test_metric_file(&owner.id, &org_id, None);
+    diesel::insert_into(metric_files::table)
+        .values(&metric)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 3. Create owner permission for owner and CanView for shared user
+    let now = Utc::now();
+    let owner_permission = AssetPermission {
+        identity_id: owner.id,
+        identity_type: IdentityType::User,
+        asset_id: metric.id,
+        asset_type: AssetType::MetricFile,
+        role: AssetPermissionRole::Owner,
+        created_at: now,
+        updated_at: now,
+        deleted_at: None,
+        created_by: owner.id,
+        updated_by: owner.id,
+    };
+    
+    let shared_permission = AssetPermission {
+        identity_id: shared_user.id,
+        identity_type: IdentityType::User,
+        asset_id: metric.id,
+        asset_type: AssetType::MetricFile,
+        role: AssetPermissionRole::CanView,
+        created_at: now,
+        updated_at: now,
+        deleted_at: None,
+        created_by: owner.id,
+        updated_by: owner.id,
+    };
+    
+    diesel::insert_into(asset_permissions::table)
+        .values(&vec![owner_permission, shared_permission])
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 4. Create test client
+    let client = TestClient::new().await;
+    
+    // 5. Send update sharing request as unauthorized user
+    let response = client
+        .put(&format!("/metrics/{}/sharing", metric.id))
+        .with_auth(&unauthorized_user.id.to_string())
+        .json(&json!([
+            {
+                "email": "shared@example.com",
+                "role": "CanEdit"
+            }
+        ]))
+        .send()
+        .await;
+    
+    // 6. Assert response is forbidden
+    assert_eq!(response.status(), StatusCode::FORBIDDEN);
+    
+    // 7. Check that permission was not updated
+    let permissions = asset_permissions::table
+        .filter(asset_permissions::asset_id.eq(metric.id))
+        .filter(asset_permissions::identity_id.eq(shared_user.id))
+        .filter(asset_permissions::asset_type.eq(AssetType::MetricFile))
+        .filter(asset_permissions::identity_type.eq(IdentityType::User))
+        .filter(asset_permissions::deleted_at.is_null())
+        .load::<AssetPermission>(&mut conn)
+        .await
+        .unwrap();
+    
+    assert_eq!(permissions.len(), 1);
+    assert_eq!(permissions[0].role, AssetPermissionRole::CanView); // Role should not change
+}
+
+#[tokio::test]
+async fn test_update_metric_sharing_invalid_email() {
+    // Setup test database connection
+    let mut conn = get_pg_pool().get().await.unwrap();
+    
+    // 1. Create test owner
+    let owner = create_test_user("owner@example.com");
+    let org_id = Uuid::new_v4();
+    diesel::insert_into(users::table)
+        .values(&owner)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 2. Create test metric
+    let metric = create_test_metric_file(&owner.id, &org_id, None);
+    diesel::insert_into(metric_files::table)
+        .values(&metric)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 3. Create owner permission
+    let now = Utc::now();
+    let owner_permission = AssetPermission {
+        identity_id: owner.id,
+        identity_type: IdentityType::User,
+        asset_id: metric.id,
+        asset_type: AssetType::MetricFile,
+        role: AssetPermissionRole::Owner,
+        created_at: now,
+        updated_at: now,
+        deleted_at: None,
+        created_by: owner.id,
+        updated_by: owner.id,
+    };
+    
+    diesel::insert_into(asset_permissions::table)
+        .values(&owner_permission)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 4. Create test client
+    let client = TestClient::new().await;
+    
+    // 5. Send update sharing request with invalid email
+    let response = client
+        .put(&format!("/metrics/{}/sharing", metric.id))
+        .with_auth(&owner.id.to_string())
+        .json(&json!([
+            {
+                "email": "invalid-email-format",
+                "role": "CanView"
+            }
+        ]))
+        .send()
+        .await;
+    
+    // 6. Assert response is bad request
+    assert_eq!(response.status(), StatusCode::BAD_REQUEST);
+}
+
+#[tokio::test]
+async fn test_update_metric_sharing_nonexistent_metric() {
+    // Setup test database connection
+    let mut conn = get_pg_pool().get().await.unwrap();
+    
+    // 1. Create test user
+    let user = create_test_user("user@example.com");
+    diesel::insert_into(users::table)
+        .values(&user)
+        .execute(&mut conn)
+        .await
+        .unwrap();
+    
+    // 2. Create test client
+    let client = TestClient::new().await;
+    
+    // 3. Send update sharing request with non-existent metric id
+    let nonexistent_id = Uuid::new_v4();
+    let response = client
+        .put(&format!("/metrics/{}/sharing", nonexistent_id))
+        .with_auth(&user.id.to_string())
+        .json(&json!([
+            {
+                "email": "share@example.com",
+                "role": "CanView"
+            }
+        ]))
+        .send()
+        .await;
+    
+    // 4. Assert response is not found
+    assert_eq!(response.status(), StatusCode::NOT_FOUND);
+}
\ No newline at end of file