Tesla shares fell about 5% in early trading on Tuesday after US regulators opened an investigation into a fatal crash in Texas involving a Tesla Model 3. The National Highway Traffic Safety Administration announced late Monday it had opened a special crash investigation into the accident, which occurred in Katy, Texas, near Houston, where a Tesla vehicle struck a home, killing 76-year-old Martha Avila. According to Harris County authorities, the driver, Michael Butler, told investigators he had been using Tesla's partially automated driving systems when the vehicle left its lane and crashed. Tesla executives disputed aspects of the driver's account; Chief Executive Elon Musk questioned whether Tesla's Full Self-Driving system could have been responsible, writing "FSD drives slowly through neighborhood streets and this was a high speed crash!" Tesla Vice President of Autopilot and AI Ashok Elluswamy wrote that "the driver manually overrode self-driving by pressing the accelerator all the way to 100% of the accel pedal" and "reached a speed of 73 mph during the crash." The competing accounts remain under investigation. The broader market also declined, with the S&P 500 falling 1% and the Nasdaq Composite declining 1.5%. UBS reiterated its Neutral rating on Tesla with a $364 price target and raised its second-quarter delivery forecast to 405,000 vehicles.