Open Source Risk in M&A Due Diligence

When you acquire a software company, you acquire its dependency tree, and that tree carries risk the financial statements do not show. Open source risk in M&A due diligence is the discipline of finding that risk before the deal closes, while there is still room to price it. A target may run components that have relicensed, may ship a product that carries copyleft obligations it never satisfied, or may face a commercial license demand that lands the day after close. Each of these reduces the value of what you are buying, and each is invisible unless someone looks. This article explains where the exposure hides, how it moves valuation, and what diligence should cover.

The article sits under the pillar on M and A and compliance and supports our open source M and A due diligence service. It speaks to acquirers, deal teams, and the investors who carry the risk if the exposure surfaces after the wire clears.

Where the exposure hides in a target

A target's open source exposure lives in places a standard data room does not surface. The first is relicensing. A component the target adopted years ago under an open license may have changed terms since. The recent wave is the obvious case: HashiCorp moved Terraform, Vault, Consul, Nomad, and Packer to the Business Source License as of August 2023, Redis moved to the Redis Source Available License and the Server Side Public License as of March 2024, and Elasticsearch and Kibana moved to the Server Side Public License and Elastic License in 2021. If the target depends on a relicensed version, it is running under terms it may not have recognized, and the acquirer inherits that position.

The second place is copyleft. A target that ships software to its own customers may embed components under the GNU GPL or AGPL, and distribution can trigger obligations including making corresponding source available. If the target never met those obligations, the acquirer buys the gap. The third place is transitive dependence, where the risky component is pulled in indirectly and appears on no inventory the target keeps. A complete dependency map is the only way to see all three, and most targets cannot produce one, which is why the acquirer has to build it during diligence. The concrete obligations are set out in copyleft distribution obligations explained.

Why it moves the valuation

Open source exposure moves valuation because curing it costs money and time, and a forced commercial license carries a price. If the target depends on a relicensed component central to its product, the acquirer faces a choice after close: pay for a commercial license sized to the combined entity, migrate to a fork such as OpenTofu, Valkey, or OpenSearch, or replace the component. Each path has a cost, and that cost is a real reduction in the value of the asset. A copyleft obligation that reaches a shipped product can be more serious still, because remedying it may mean releasing source the target considered proprietary.

The point of diligence is to convert these from surprises into priced line items. An exposure found before close can be reflected in the price, addressed through representations and warranties, or made a condition of the deal. The same exposure found after close is a loss the acquirer absorbs alone. Quantifying the exposure, with a cost to cure attached, is what gives the deal team something to negotiate with, the method covered in quantifying open source risk for a deal.

What diligence should cover and when

Thorough open source diligence on a target covers five things. It builds a full dependency tree, direct and transitive. It records the license state of every component, including any that have relicensed since adoption. It checks copyleft and distribution obligations against how the target actually ships its product. It attaches a cost to cure to each material finding. And it produces a red flag memo the deal team can act on, ranked by impact. This is the same discipline as an open source license risk assessment, applied to an asset you do not yet own and run against a deal clock. The full sequence is set out in the open source due diligence checklist.

Timing decides whether the work pays off. Diligence has to happen early enough that findings can shape the price or the agreement, not as a confirmatory step after terms are set. An acquirer who learns of a relicensed dependency in week two can price it, seek a representation, or require remediation as a condition. One who learns in the final week has little room left. The acquisitions themselves underline the stakes: IBM later acquired HashiCorp, a reminder that the companies behind these components are themselves deal targets, and that license posture travels with the asset. For exposure that sits specifically in an acquisition target, see relicensing exposure in an acquisition target. The throughline is simple: look early, attach a number, and the exposure becomes something you price rather than something that prices you.

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