How does a business, like a lender, report information about its customers to a credit bureau?

Unlike personal credit there aren't three or any really major players that monitor business credit and the creditworthiness of businesses. For personal credit you have the major bureau's but business aren't like that.

There are many players out there but a lot of them are industry specific. What you really need to do is talk to other suppliers of the business in question. Do they pay on time with them? Also if your going to do a lot of business with them you will want to take a look at the financial statements to see how they are doing. Also you can start them out with a small credit line and see how they do in meeting their payment terms.

I could go on forever but it's really not worth it. If you have any follow up questions let me know.