When you're acquiring a company, there are a number of factors you have to
First, timing. You make an offer. It gets accepted. Terms are not always final at this stage especially due to regulatory approval, but sometimes only directionally specified. A press release goes out. Employees, partners and customers learn of the deal. Because terms are not concrete, announcing anything beyond price and high level assurances is unwise. Regulatory approval gets underway. Terms change to meet regulatory approval where appropriate. During this time, the companies may not act as one. Everything needs to keep going as is. Acquisition closes and the company releases a short statement, normally without terms.
Second, what's the right thing to do by the employees. Disclosing terms can disclose private financials of some of the founding team or major employee stake holders. If terms include evaluation of a sale of a unit, demotiving employees serves no purpose for the company or for them. Terms may include shutting down part of a business, moving an office, exiting a market or killing off an internal competing product. Employees should not find any of this out in a press release. That's just crazy and 19th century.
Next, what's the right thing to do by the customers. The customers of both companies may be impacted by an acquisition. Disclosing terms that telegraph this without having the time or ability to put a plan in place will destroy sales and customer confidence.
Next, what's the right thing to do by partners. Partner or channel relationships will need to be reconciled and may require renegotiation. Without a clear understanding of what the two companies want, which may take months of planning, releasing terms that frighten or confuse partners is counter productive.
Next, what's the right thing to do by investors. Announcing terms that will have a material impact of unknown magnitude at the time of the announcement could very adversely and unnecessarily affect investors. There are some cases where the effect can be positive, and these are usually announced, like the definite sale of a unit or location to appease regulators (forgone conclusion) or the price which would be fixed at the time of the deal.
Lastly, what's the right thing to do by the deal team. Acquisitions are complicated and difficult. It's nearly impossible to find ways to accurately articulate the full set of terms of a deal, especially when even the slightest misconception or slight PR mistake could lead people to think they may lose their jobs, when the product they depend on is in jeopardy, their sales numbers might plummet, or their wealth will shrink. This is doubly true when the execution of terms is far more important than the terms themselves.
For tiny acquisitions, it's just not worth the effort.