Regulation D
The US private placement exemption behind most syndications and accredited-only fractional deals. No cap on the raise, but limits on who can buy.

Table of contents
What it is
Regulation D is the set of SEC rules that let a company sell securities privately without registering them. There is no limit on how much can be raised and no SEC review of the offering document. In exchange, the sale is restricted to investors the rules consider able to look after themselves, and the shares are restricted from public resale. It is the oldest and most used exemption in real estate. Most syndications, most private real estate funds and most accredited-only fractional listings are Regulation D offerings.
506(b) and 506(c)
Rule 506(b) allows unlimited accredited investors plus up to 35 sophisticated non-accredited investors, but forbids general advertising. The sponsor may only offer the deal to people it already has a relationship with. Investors self-certify their status. Rule 506(c), added in 2013, allows the sponsor to advertise publicly, on a website, in an email, on a platform, but every buyer must be accredited and the sponsor must verify it, usually with tax returns, bank statements or a letter from an accountant or lawyer. Fractional platforms that list accredited-only deals almost always use 506(c), because a public listing is advertising. That is why they ask for documents rather than a checkbox.
What it means for you
If you are not accredited, Regulation D deals are closed to you, and no platform can lawfully let you in. Look for Regulation A+ or Regulation Crowdfunding offerings instead. Threeworld marks listings that require accreditation so you can filter them out. If you are accredited, remember that the lighter rules cut both ways. There is no SEC review of the document, the sponsor sets the terms, and the shares are restricted for at least six months to a year. The private placement memorandum is the whole story, so read it in full.
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All articles
Regulation & Access
Accredited Investor
Who counts as an accredited investor, why some fractional real estate offerings require it, and what is open to everyone else.

Ownership & Structure
Syndication
How real estate syndications work, how they compare with fractional platforms, and who can invest in them.

Regulation & Access
Regulation A+
How Regulation A+ works, why fractional real estate platforms use it to sell to everyone, and what its investor protections and limits are.