The flavor of the month in startup fundraising is the "initial coin offering," a seemingly unregulated method of capital raising that has allowed tiny, unknown companies to raise tens or even hundreds of millions of dollars. Not everybody's going down this road, however. Digital Asset Holdings LLC, a New York-based startup building new technology products for financial-services firms, decided to raise money the old-fashioned way. The firm, run by former J.P. Morgan Chase & Co. trading...