There are services such as Dunn and Bradstreet, which provides financial ratings. The first thing I would do is see whether Bloomberg has a write-up. Depending on what I find, I would either approach the company looking for information or turn to a company which does investigations to get a deeper background check.
Questions & answers
How do we investigate a private company in the U.S.?
We own a manufacturing company in China. After some research we found a company in the U.S. that produces the type of products we are interested in. We are considering acquiring this company so we can bring their products to the market in China. However, this is a private company and we can’t find much information about it online. We want to know more about their financial situation. What are the proper ways to get the information we need?
There are corporate mergers & acquisitions advisors who you should go to for sourcing the company information and approaching the owners up to completion of the deals. They are professional in terms of negotiating the terms on your behalf and understanding the key concerns on both sides. In general, they are helpful to progress the deal with the owner. Better than you approach the owner directly. You may sign into a consultancy agreement with such advisor and they will act on your behalf to approach the owner of the target. They will come up with the LOI and the following documents for you and your lawyer's review. They will evaluate the terms from the market practice.