The Mustangs turned the ball over on their first two possessions leading to two TCU touchdowns.
The Horned Frogs got field goals on their final two drives to take a 20-0 lead into halftime.
SMU quarterback Bo Levi Mitchell is 10 for 15 for 91 yards with no touchdowns and one interception. His main target Cole Loftin has three receptions for 46 yards.