In many cases, what you read about as "acquisitions" are actually "asset sales," meaning that the seller and the acquirer have specifically agreed on what asset

In many cases, what you read about as "acquisitions" are actually "asset sales," meaning that the seller and the acquirer have specifically agreed on what assets have been transferred (say, real estate, IP, brand names, machine tools, whatever), and what have not. Similarly for liabilities. There are, of course, laws relating to fraud, consumer protection, etc. It's only when you actually acquire the company (buy the outstanding shares) that basically "everything" transfers to the purchaser. And even there, they can agree on carveouts for specific liabilities or other things, such as existing customer support.