text: when you end a sentence with yahoo! do you need a full stop? yahoo! is a noun, right?  the exclamation mark is part of the company name.  so if i'm writing a sentence that finished with the company name, yahoo!, do i need extra punctuation? you've just answered your own question by putting a comma after the exclamation mark in yahoo!.  if you need to put a comma after the exclamation mark, why don't you need to put a full stop? if you think you don't need to add a full stop after yahoo!, then would you ask a question with yahoo! at the end of it without the question mark?  now, having a company name with a period at the end would be really confusing.