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The experience of Social Finance, which announced a new CEO on Tuesday, shows how the biggest names in fintech, while generating massive financial support, still operate in a very volatile world.

Twitter executive Anthony Noto will have to demonstrate to Wall Street he can overhaul the firm's corporate culture, lay the groundwork for an IPO and determine whether to renew SoFi's pursuit of a bank charter.

Not every fintech is a magnet for sensational headlines. Counting down the top fintechs by valuation, partly based on research according to Forbes, the list includes several firms, such as Avant and Stripe, that have managed to attract funding, develop friendly partnerships with banks and mold successful business models.