Arch Capital (ACGL), a $34B specialty insurer I've been researching. Here's my analysis. Arch Capital (ACGL), a $34B specialty insurer I've been researching. Here's my analysis. been working through Arch Capital for the past few weeks and wanted to get my notes down somewhere. posting here because I'd genuinely like to hear what I'm getting wrong. short version of why I bothered. it's a specialty property and casualty insurer, plus reinsurance, plus mortgage insurance. roughly $34B market cap. trades around $97 today. tangible book is $61.71 a share, so 1.56x book. they've grown book value per share at over 15% a year for 23 years. that's the kind of compounding that usually doesn't sit at 1.5x book for very long. the way insurers actually make money is they collect premiums today, pay claims later, and get to invest the gap in between. that gap is called float. Arch sits on $24B of it.…