Core terms
Registered direct offering (RDO)
A sale of registered shares, often with warrants, directly to a small group of investors through a placement agent, usually off an effective shelf registration. It is announced and priced quickly, often overnight or before the open.
In a registered direct offering, the company has an effective shelf (often on Form S-3) and sells shares to pre-selected investors, typically institutions, with a placement agent arranging the deal. The terms are disclosed in a press release and a prospectus supplement filed under Rule 424(b). Smaller companies are limited by the "baby shelf" rule, which caps sales off an S-3 to one-third of public float in any 12 months.
Pricing is usually below the last trade. Many deals pair the shares with warrants, sometimes sold in a concurrent private placement, which add potential future shares on top of the shares sold now.
What traders should verify
Read the 424(b) for the price, share count, warrant terms and any lock-up, and compare the price with where the stock is trading.
Do not conflate
Market usage; the securities rules define registration and the prospectus, not the "RDO" label. Announcement timing does not by itself predict the price reaction.
Primary source
Trader usage: there is no official definition, and platforms and tools may calculate it differently.