Investing in companies with sub-$1 billion market caps can be a tricky business. After all, if it were easy to figure out what stocks are destined to be future mid-cap or even large-cap stocks, we'd all be rich.

Having said that, there are some that look extremely attractive from the perspective of a long-term investor. Both of these companies have massive market opportunities to pursue as well as management teams with ambitious visions for the future. Here's a bit about each one, and why you might want to put them on your radar.

Limitless potential to grow

Boston Omaha Corporation (BOC -1.30%) is a very small business right now in the context of publicly traded companies, with a market cap of just $532 million. But management has big ambitions.

Boston Omaha is an early-stage conglomerate with four major business segments. It owns a billboard advertising business that has lots of potential to grow, especially when it comes to digital advertising faces. It has an insurance subsidiary focused on surety insurance, which can be a highly profitable business. Third, the company has several broadband internet service businesses that generate steady, high-margin income after the initial capital investment.

Last but certainly not least is the Boston Omaha Asset Management (BOAM) business, which so far has mainly invested in minority stakes in other companies. It owns a stake in an auto lender, commercial real estate brokerage, and several others, as well as a 23% stake in aviation infrastructure company Sky Harbour. However, the company's vision is to start raising outside capital to manage and deploy in high-potential opportunities. It is currently in the process of raising capital for a built-to-rent housing fund and sees a massive opportunity to raise money to pursue broadband infrastructure opportunities. The company has over $100 million in cash itself, but this could allow it to generate a large stream of fee income in addition to investing its own capital.

To be sure, there is a lot of execution risk involved with building an asset management business, let alone an entire conglomerate of businesses. But if management can execute on its vision, this could be a home run for patient investors.

A market that is really in need of disruption

The real estate market is just begging to be disrupted. For one thing, the process of buying a home is clunky at best. Negotiating prices, applying for a mortgage, finding homeowners insurance, and other aspects of the home-buying process are highly inefficient and make something that should be a happy event into a month (or more) of frequent frustration. And that's not to mention that the commission structure for real estate transactions has been largely unchanged for the past few decades despite massive advances in the technology that real estate professionals use to do their jobs.

Redfin (RDFN 8.49%) has already done an excellent job of building an online real estate platform as well as a brokerage that aims to disrupt the traditional pricing structure, but the company could still be in the early stages of its evolution. It has saved its customers an estimated $1.5 billion in real estate commissions since launch, and its platform averaged 50 million unique visitors per month last year.

However, there are some parts of the business that are just getting warmed up. The 2021 acquisition of rental housing platform Rent is not only a fast-growing part of Redfin; it also creates a natural marketing funnel as renters graduate to home ownership. Its mortgage and title service businesses have done a great job of growing but still have lots of room to go. Plus, Redfin is doing an impressive job of building out its technology for home sellers, as well as figuring out additional ways to monetize the traffic to its platform, including partnerships with Zillow and Opendoor.

With a market cap of just $930 million and management forecasting profitability by the end of 2024, now could be a great time to take a closer look at Redfin while the real estate market is still very slow.

Two very different businesses

Investing in smaller, high-potential growth companies isn't for the faint of heart, and these two stocks are no exception. And these are two very different types of businesses. Boston Omaha hopes to build a self-sustaining capital-generation machine that can grow and compound over time, and Redfin aims to leverage technology to disrupt one of the largest industries in the market.

Both companies are likely to have some major growing pains in the years ahead, and investors should expect significant volatility along the way. But if the management teams of these companies can execute on their respective visions, they could certainly become all-star businesses that are many times larger than their current size.