Morningstar is nearing a deal with federal regulators over allegations the firm violated rules in its bond-rating business that prohibit analysts who hand out credit ratings from being involved in sales and marketing for their companies, according to people familiar with the matter.

The potential settlement with the Securities and Exchange Commission is an embarrassment for a firm that made its name analyzing mutual funds. Morningstar has made a big push into bond ratings, saying it would improve quality and restore investor trust in the business, whose reputation was damaged in the financial crisis.