What caused Silicon Valley Bank to fail?

According to its website, Silicon Valley Bank provided banking services about 35 years with the country's venture capital-backed technology and life-science companies, as well as more than 2,500 venture capital firms.
Silicon Valley Bank, flush with cash from high-flying start-ups, did what most of its competitors did for decades: it kept a small portion of its deposits in cash and used the rest to buy long-term debt such as Treasury bonds. Unfortunately, when interest rates were low, these investments promised consistent, modest returns.But, as it turned out, they were shortsighted. The bank had overlooked what was going on in the broader economy, which had become overheated after more than a year of pandemic stimulus. 

As a result, Silicon Valley Bank was left in the dust when the Federal Reserve began raising interest rates to fight against rapid inflation. As newer government bonds came with more interest, those once-safe investments became less appealing. However, rising interest rates are not the only source of Silicon Valley Bank's problems. The bank was one-of-a-kind in ways that contributed to its quick demise. Because Silicon Valley Bank's business was concentrated in the tech industry, the bank began to experience difficulties when start-up funding began to dwindle, prompting its clients — a mix of technology start-ups and their executives — to tap their accounts more frequently.
The bank also had a number of large and uninsured depositors — the type of investors who tend to withdraw their funds. 

Following the disclosure of Silicon Valley's massive loss on Wednesday 15 March, 2023, the tech industry panicked, and start-ups rushed to withdraw their funds, resulting in a bank run. Silicon Valley Bank was in free fall early March 2023. The federal regulator controls approximately $175 billion in customer deposits as a result of the takeover according to The New York Time.