A internet tablet from Apple, to be offered by Verizon, would have a negative impact on BlackBerry maker RIM according to at least one Wall Street analyst. While the product is nothing more than a rumor at this point, it is enough for UBS analyst Maynard Um to downgrade his opinion of the shares of the Canadian cellphone manufacturer. According to the The Street.com, the new Apple device is expected before the holidays. Um points out that Big Red is one of RIM's top three customers, accounting for 10% to 25% of the firm's quarterly revenue. While the tablet would be data only, it could quickly become a top-selling item for Big Red, pushing business away from BlackBerry products. And once the carrier has opened it's door to an Apple product, the thinking is that a Verizon branded iPhone would follow fairly quickly. The UBS analyst does note that his concerns are emotional as opposed to material, but emotions do go a long way in pricing a stock on Wall Street.