Square isn't just disrupting the cash register. It's also disrupting the bankers lending cash to small businesses via a new program called Square Capital. Apple (NASDAQ:AAPL) should either copy or invest in what Square is building.

How to earn 10% interest without trying
The idea is simple. Retailers sell a portion of future sales in exchange for an up-front capital infusion. So, for example, let's say Square lends your business $10,000. You repay $11,000 a transaction at a time, taken as 10% of each day's sales. No minimums required.

Banks aren't as forgiving, and rightfully so, since lending to entrepreneurs tends to be a tricky business. In 2009, nearly 12% of Small Business Administration loans defaulted, up from a reported 7.4% in 2005 -- startling numbers that suggest Square Capital will suffer serious losses at some point.

On the other hand, Square processes millions of transactions daily. Those bits and bytes of information  are revelatory, helping the company to determine a proper-sized capital infusion without vetting a business plan or checking a credit score. For Square, data determines default risk.

Niche oriented
Of course, Square isn't the only company with this sort of information handy. Amazon.com also processes an extraordinary number of transactions. The difference is that while Square serves mom-and-pop shops, Amazon serves itself and drives Ma and Pa out of business.

Contrast that with iTunes and the App Store, which enable commerce for the enterprising. Apple has paid iOS developers at least $15 billion since inception and today serves nearly 800 million iTunes accounts. Few are as privy to the inner workings of digital businesses.

Now consider what we saw at this week's Worldwide Developers Conference. HealthKit represents a foray into health data management. HomeKit is Apple's attempt to unite the competing elements of home automation. CEO Tim Cook's plan is to grow by dominating interesting, important niche markets. A RetailKit with the iPad at the center can't be far off.

Mr. Cook? Yes, your $2 billion is right here
Think about it. Square already supplies the key equipment that turns an iPad into a cash register. Investing in Square Capital -- or offering an alternative -- could help Apple tip the scales and dominate the estimated $2 billion market for mobile point-of-sale (POS) systems while putting a portion of its $150 billion-plus in cash and investments to work earning interest at far above-market rates.

Small business financing is changing. Apple can either accelerate the shift and profit or get left behind. Do you agree? As an investor, what other verticals would you like to see Apple pursue? Leave your thoughts in the comments box below.

Square Capital holds special appeal to small businesses. Credit: Square.