What is a Rule 506(b) offering?

Rule 506(b) is the workhorse private-placement exemption: a company may raise unlimited amounts from accredited investors (plus up to 35 sophisticated non-accredited ones) without SEC registration — but may not generally solicit or advertise the offering.

The no-solicitation rule is why most raises are quiet: investors must come through existing relationships. Investors self-certify accredited status, a lighter burden than 506(c)'s verification.