IP assets are often sold at auction or in private transactions. Private equity firms and patent licensing companies play in this space.

For example Fortress (now owned by SoftBank) cut a deal for Theranos’ IP: https://www.marketwatch.com/story/theranos-closes-deal-with-...

In this case, when there is absolutely no intellectual property to talk about, everyone huddles down and hopes that no one notices their investment. In other cases, the proprietary body attempts to sell the IP to cover debts. Shareholders walk but are usually eligible to pay for the IP at the same rate as any other buyer. Sometimes this is used by shady boards to get control of a company and their IP.