How long does it take to do an acquisition? If the buyer is serious and focused, the principal terms and deal structure can be worked out in a few weeks. From there, expect 30–90 days for due diligence, definitive docs, closing, etc. Overall, probably 3–6 months is a basic timeline for most M&A deals. Yes M&A's can take longer, but most likely the old pumps are dead. IMO.