There are two perspectives here: that of the purchaser in the deal and that of the vendor.


From the vendor's perspective, a "deal is done" when:

•  the terms of the contract are fulfilled and consideration satisfied;
• there are no blow-back issues such as misrepresentation, fit for purpose, etc claimed by the buyer against the vendor;
• all latent warranties, potential liabilities and other obligations from the vended asset expire, are expunged or transferred out;
• the impacts on the vendor's company from the sale of the asset have been neutralised.

From the purchaser's perspective, a "deal is done" when:

•  the terms of the contract are fulfilled and consideration satisfied;
• no hidden issues are discovered that escaped due diligence such as misrepresentation, fit for purpose, etc claimed by the vendor;
• the impacts on the purchaser's company from the purchase of the asset have been incorporated.