Able to Type a Period (.) within a Company Name when Retrieving an Existing Company in the Address Book
You can't retrieve a Company in the Address Book that has a Period (.) in the name by typing it out - you have to scroll down since the period isn't recognized when being typed.
Jin Yu commented
You should be able to search a company name with period such as "Apple Inc."
Did you search in Quick Search? Can you provide an example that the search cannot find?