All eyes were on Apple Wednesday as shares of the tech giant soared to an all-time high of $101.09 per share on renewed faith in CEO Tim Cook.
Wednesday's move was the first time the company has surpassed $100 per share, a key psychological level for investors, since September 2012. Apple now has a market cap of more than $600 billion, more than Google and Amazon combined.
So, as Apple's highly anticipated iPhone 6 is reportedly set to be unveiled on Sept. 6, how much bigger can the company actually get?
"I think the challenge of Apple is it's got this incredible ecosystem, it is a massive company," said Envestnet's head of global strategy and CNBC Contributor Zachary Karabell, "but I do think that they are inherently in a hardware business and even with the massive success of iTunes and the app store, they do need to keep creating that next wave of product."
Karabell joked that not only does he own Apple shares, but he's also an avid iPhone user. However, he voiced concern about the company's sustainability. "I'm always a little wary of that next release, the 5s was fine, it had innovation but it wasn't amazing," he added. "How many releases can have that response before people turn somewhere else? I think we need to constantly be on the lookout for that because we have a franchise that's incredibly powerful and simultaneously vulnerable."
John Kosar of Asbury Research is bullish on the stock medium-to-long-term, but suggested a better buy would be on a short-term pullback. "We're up against a major resistance level at the old highs," he said. "I would be looking to buy some kind of a break here. The 50-day moving average is about 6 percent underneath the market at $94.75 [per share]. I think that is the feasible place to buy."