What registration actually buys, which is the whole of the consumer stake. Registration is a disclosure process rather than an endorsement: it means the issuer has filed a registration statement containing prescribed information, not that anyone has judged the investment sound. The SEC's summary of the consequence is that "generally speaking, unregistered offerings are not subject to some of the laws and regulations that are designed to protect investors, such as disclosure requirements that apply to registered offerings." So the practical difference for a buyer is the volume, format and legal backing of the information they get before deciding, and their ability to find the same information later without asking the seller for it.
The SEC's ten red flags, which are the operational content of this page. In its investor alert 10 Red Flags That an Unregistered Offering May Be a Scam, dated August 4, 2014, the Office of Investor Education and Advocacy lists: claims of high returns with little or no risk; unregistered investment professionals; aggressive sales tactics; problems with sales documents; no net worth or income requirements; no one else seems to be involved; sham or virtual offices; not in good standing; unsolicited investment offers; and suspicious or unverifiable biographies of managers or promoters.
Four of those are worth expanding, because they are the ones a reasonable person is least likely to weigh correctly.
"No net worth or income requirements" is a red flag because the absence of a gate is itself the signal. Federal law limits many private offerings to accredited investors, so an issuer running a legitimate exempt offering has a reason to ask about a buyer's finances. The SEC's instruction is to "be highly suspicious of anyone who offers you private investment opportunities without asking about your net worth or income." A pitch that skips the question has either not thought about the exemption it is relying on or is not relying on one. What the thresholds are, and who meets them, is set out on our page about the accredited investor.
"No one else seems to be involved" describes missing infrastructure. The SEC notes that "usually, brokerage firms, accountants, law firms, or other third parties are involved in a private offering," and adds a second half that is easy to skim past: "be cautious if you are told not to contact someone who is supposedly involved with the investment." A deal with no professionals attached, or with professionals the buyer is discouraged from calling, is a deal with nobody to corroborate it.
"Not in good standing" is the cheapest check on the list. Any company seeking investment, including a limited liability company or limited partnership, should be listed as active or in good standing in the state where it was formed, and every state maintains a searchable register of its companies, usually through the Secretary of State. A company that cannot be found there, or that is listed as delinquent, is a five-minute finding.
"Sham or virtual offices" is about exemption shopping. The SEC's concern is that "a company may establish a mailing address within a state in which it has no legitimate operations in a fraudulent attempt to qualify for an exemption from registration." An address in a state where the business has no headquarters, plant or other physical operations is evidence about the exemption being claimed, not merely about the company's tidiness.
Where this sits relative to the fraud itself. An unregistered offering is a container, not a scheme. If the money raised through one is used to pay earlier investors, that is a Ponzi scheme; if the deal spreads through a congregation or a profession, that is affinity fraud; if the pitch promises a high return with no risk, that is the guaranteed-return tell. The legal conclusion for all of them, where the instrument is a security, is securities fraud, and our page on that covers how the antifraud provisions reach conduct the registration rules never had to describe. What the registration question adds is a specific, early, checkable line of inquiry, available before any of those characterizations can be made.