What Is a Shelf Offering (and Why Do Stocks Drop on One)?

• →S-3: the shelf registration. It says the company may sell up to some amount of securities over the next three years. On its own it is a warning, not a sale.
• →424B5: the prospectus supplement for a specific takedown. This is the document that prices the deal.
• →At-the-market (ATM) program: a shelf used to drip shares into the market over time instead of one priced deal.

The market reacts when the offering is announced, often in an after-hours press release or 8-K. The 424B5 that prices the deal is filed after that reaction, so an alert built on the 424B5 is usually late. InsiderWatch treats offering news from the announcement (8-K or wire) as the event, and publishes 424B5-sourced calls as context rather than as directional alerts, because the shadow data showed those calls were chasing a move that had already happened.

What matters is the offering as a share of the existing float and the discount to the last price. A 5% raise at a 2% discount is routine for a growing company; a 30% raise at a 20% discount from a company burning cash is a distress signal.

Form S-3 is available to companies that have filed SEC reports on time for at least twelve months. A company with a public float of $75 million or more can register an unlimited amount for primary sales. Below that, the "baby shelf" rule caps sales at one third of the float in any twelve-month period, which is why small companies raise money in repeated small tranches. The largest companies qualify as well-known seasoned issuers and file an automatic shelf (S-3ASR) that is effective on filing, letting them sell the same day they decide to.

• →424B5: the prospectus supplement for a takedown from a shelf. The one that prices the deal.
• →424B3: a prospectus that updates an earlier one, often used for resale registrations where existing holders, not the company, will sell.
• →424B4: the final prospectus for an initial public offering.
• →424B7: a supplement adding selling stockholders.

A 424B5 from the company is dilutive: new shares are created. A resale prospectus is not: shares that already exist change hands. The two are often confused in headlines that say "files to sell shares".

• →Underwritten offering: banks buy the shares and resell them, usually announced after the close and priced overnight at a discount to the last trade.
• →Bought deal: a bank buys the whole block at a fixed price, moving the risk off the company within hours.
• →Registered direct offering: shares sold from the shelf directly to a handful of investors, common among small caps and often accompanied by warrants.
• →At-the-market program: a sales agent sells shares into the market over months at prevailing prices. The company files the agreement once and reports sales quarterly, so there is no single event to react to.
• →Over-allotment (greenshoe): an option for the underwriters to buy up to 15% more shares at the offering price, exercised when demand is strong.

Three numbers: the size of the raise as a share of the existing float, the discount to the last close, and the company's cash runway before the raise. A company with two years of cash raising 5% at a 3% discount to fund growth is a routine event. A company with two quarters of cash raising 40% at a 25% discount with full warrant coverage is a distress signal, and the shares will usually find the offering price rather than the previous close. Use of proceeds, stated in the prospectus, separates "general corporate purposes" from a named acquisition or debt repayment.

The timing lesson in the section above applies to every kind: by the time the pricing document is public, the reaction has usually happened. InsiderWatch grades offerings from the announcement and treats the later pricing filing as confirmation, and its record shows offerings on liquid, well-covered names are less reliable as a bearish call than offerings on small companies, so the largest names are sent as context.