WooCommerce Bulk Stock Management:
Bulk manage stock levels and print out stock lists from admin
The bulk stock management extension gives you a new interface (found in Products > Stock management) which lists your products and variations along with their stock properties.
Products can be filtered by product type, stock management status and stock status, and ordered by name, ID, SKU or stock quantity.
Via the input field you can easily set the stock quantity for multiple products at once. There are bulk actions for setting the stock status too.