Hints that U.S. regulators could veto Comcast Corp's proposed $45 billion takeover of Time Warner Cable Inc have investment bankers worried about whether they will get paid, with smaller advisory firms particularly on edge. Boutique investment banks such as Allen & Company, Centerview Partners and Paul Taubman's PJT Partners have limited resources compared to their larger brethren, and they use them to win mandates on a few big deals.