An arbitration panel issued an award worth more than $5.8 million against the securities unit of Deutsche Bank AG (DB), siding with three Florida brothers who said they lost money after they were put into several risky alternative investments.

The arbitration panel last month ruled in favor of Charles, John and Robert Switzer, from Pensacola, Florida. According to a lawyer for the brothers, the three became instant millionaires in the late 1990s when a company that was founded by a family member went public, allowing them to tap into their inherited stock in Lamar Advertising Co. (LAMR).

One of the underwriters in Lamar’s initial public offering was Alex. Brown, a securities firm that later merged with Bankers Trust, which itself eventually merged with Deutsche Bank. After the IPO, Alex. Brown signed up the Switzers as brokerage clients. Over time, the three brothers were each sold “seven illiquid, high-risk alternative investments for a total commitment of $8 million per brother,” according to their attorney, Alan Sparer.

The investments were made on the advice of a broker at the firm, Paul Young. There was no immediate comment from Deutsche Bank. Mr. Young’s status with the firm couldn’t immediately be determined and an attorney for Mr. Young couldn’t immediately be reached.