49. SoFi

Founders: Mike Cagney, Dan Macklin, Ian Brady, James Finnigan
Launched: 2011
Funding: $1.4 billion
Valuation: $3.6 billion
Disrupting: Banks, financial institutions
Rival: Lending Club

In the past five years, San Francisco-based SoFi (short for Social Finance Inc.) has grown into the second-largest online lender in the market (Lending Club is No. 1), having funded $9 billion in loans to date. The company was started by former big bank executives who believed there had to be a better way to lend money to hardworking men and women with good earnings potential.

Read MoreFULL LIST: 2016 DISRUPTOR 50

Student-loan refinancing was the initial focus of SoFi, but now it's expanded to mortgages, mortgage refinancing, personal loans and, most recently, wealth management services. Its offerings include personal loans up to $100,000 and mortgages in 25 states and Washington, D.C.

Millennials still account for a large portion of SoFi's customers, but now the company will be helping them not only refinance student loans (rates start at 3.5 percent versus about 4.6 percent for government-backed loans) but also with refinancing credit card debt, buying a home and saving for retirement.

The company recently started offering wealth management services in the form of low-cost exchange traded funds (ETFs) that cost $5 for every $100,000 invested, but are free to those who have a loan with the company. The first $10,000 is free regardless. The company claims its underwriting approach, proprietary technology and robust customer service is what sets it apart from other online lenders.

The strategy must be working: SoFi has increased its customer base from 20,000 to 150,000 in the last year. It also recently launched a hedge fund to buy its own loans. Co-founder and CEO Mike Cagney stated last spring that the company would be planning an IPO in the next year, but after the company raised $1 billion in new funding in September, led by Softbank Group, those plans seem to be on hold.