Wall Street isn't giving Amazon enough credit for its private label venture, which should grow to $25 billion in revenue by 2022, according to SunTrust Robinson Humphrey.

The flourishing private label business should be strong enough to help push the company's share price up more than 21 percent over the next 12 months, according to analyst Youssef Squali.

"As strong an e-commerce platform as Amazon has become over the last 20 years, we believe that the best has yet to come," Squali said in a note to clients Monday. "Private label is one of the highly under appreciated trends within Amazon, in our view, which over time should give the company a strong 'unfair' competitive advantage. 'Unfair' because it'll be very difficult to dislodge the company once it attains it; fair because it's earned, not bestowed."