Check out the companies making headlines in midday trading: Nvidia — The chipmaker tumbled nearly 16% as the performance of a language model from Chinese startup DeepSeek raised questions about the amount of investment in artificial intelligence. With that performance, the high-flying AI name is on track to notch its worst day since March 2020. Chipmakers — Nvidia wasn’t the only semiconductor company falling sharply on the DeepSeek developments. Broadcom dropped about 17%, while Micron…