The two—Gamal, once seen as heir apparent to his father, Hosni Mubarak, and businessman Alaa—were acquitted of corruption charges on June 2. They remained in custody for the insider trading trial, which opened Monday.
The case was adjourned to Sept. 8 to allow defense lawyers to read the file.
Prosecutors say the two, along with seven others, made 2 billion Egyptian pounds in illicit gains through actions that violated stock market regulations. The nine are accused of conspiring to buy 80 percent of Al Watany Bank of Egypt and then selling it, knowing a Kuwaiti bank was about to buy it.