A senior Fidelity Investments trader retired from the company last week after an internal inquiry revealed purchase of a stock in his mother’s personal account prior to Fidelity issuing orders to purchase the same security, according to people familiar with the situation.

According to securities laws, it is prohibited that money managers and traders benefit from their inside market knowledge of their company’s transactions or from transferring that information to others. The usage of that advance knowledge to trade – so-called "trading ahead" or "front running" -- can be profitable, since a stock often grows in price when a big fund company purchases it. The extent of that trading was unknown, and it wasn’t clear what person, if anyone, made profit from it. Regulators are examining the trading, according to people familiar with the investigation.

The discovery comes to light as both the Securities and Exchange Commission and the National Association of Securities Dealers are scrutinizing whether Fidelity traders received gifts from brokers engaged in business with the Boston-based company, which appears to be the nation’s largest manager of mutual funds in terms of assets, according to the Wall Street Journal. In a response to a disclosure, government investigators are examining Fidelity for the improper receipt of gifts up to potentially improper personal trading, according to people familiar with the situation. Since December, four traders have been dismissed from Fidelity, and 14 other employees have been reprimanded as a result of the gift inquiry.