please give me a short description about SVB collapse

On Friday, March 10, 2023, Silicon Valley Bank (SVB) failed after a bank run, marking the second-largest bank failure in United States history and the largest since the 2007–2008 financial crisis.[1][2] It was one of three March 2023 United States bank failures.

It's due to risk mismanagement of SVB Bank, where the bank bet on long dated treasury bond. When the bank runs happen, SVB don't have a choice but to sell those long dated bond at a steep discount and incur huge lossses.