A PIPE is faster and more certain than a public deal because the company negotiates with a handful of funds rather than marketing to the whole market. The price is discounted and the terms often include warrant coverage, a floor price, or convertible preferred rather than plain common-stock.
The resale registration is the part traders watch. Until the shares are registered the PIPE buyer cannot sell; on the day the registration goes effective, a large block becomes tradeable and often is. PIPEs are also the standard funding layer alongside a de-spac.
Example: a $12 stock raises $90M by selling 8.3M shares at $10.80, a 10% discount, plus half-warrants at $15. If the warrants are exercised later, another 4.15M shares appear at $15.
Related: private-placement, dilution, warrant, de-spac, registered-direct-offering