Not so long ago, homebuyers, entrepreneurs and investors went hat-in-hand to the bank to apply for a mortgage, small-business credit line or brokerage account. Financial technology, or fintech, is rapidly changing all that by making it easier to save, borrow and invest online or with a mobile device, without ever dealing with a traditional bank. For old-fashioned banks and money managers, fintech is causing dramatic upheaval, possibly the most since mainframe computers first whirred to life on Wall Street in the 1960s. It’s caught the attention of regulators, consumer advocates and industry veterans. Will a digitized financial-services industry mean lower costs, more innovation and greater access for all? Or will the dominant players ultimately stay on top, with their hefty fees, commissions and compensation, largely intact?