Is LinkedIn worth $1bn? Yes. Why? Because Bain Capital says it is. The stock is not public, so you and I cannot trade it. The whole notion of the average punter trading tech stocks (or the average punter's pension fund trading it on your behalf) seems rather quaint, from some bygone era. But why has the public market for tech stocks disappeared?

SolarWinds Inc., a venture-backed network management software company, filed to go public Friday, March 21, with an initial target of raising as much as $250 million. The Austin, Texas-based company, which Bain Capital Venture Integral ...