Datadog has offered nearly $4 billion to acquire cloud cybersecurity startup Upwind Security, as it seeks to expand its cloud security capabilities. Upwind has not accepted the offer.

Upwind is reportedly finalizing a $300 million funding round. The round would value the company at approximately $3.8 billion.

Datadog shares fell 5.1% after the bid was announced. If completed, the deal would be Datadog’s largest acquisition, expanding its security platform alongside its core observability products.