The first question is whether the money reached an insured bank at all, and it is not rhetorical. The FDIC states plainly that it "does not license or register deposit brokers and an unscrupulous broker could mislead or defraud its customers", and that "[i]f the broker fails to place your funds into a CD at an FDIC-insured bank; your money will not be insured by the FDIC." Deposit insurance attaches to a deposit at an insured institution, not to a transaction with an intermediary. That is why both the SEC and the FDIC tell buyers to confirm in writing which bank will hold the money and to check that bank in the FDIC's BankFind directory.
The second question is how the deposit is titled, because pass-through insurance depends on the records. Unlike a CD bought at a branch, a brokered CD is often held by a group of unrelated investors who each own a piece rather than the whole. The SEC's guidance is to confirm in writing how the CD is titled and to make sure the account records show the broker acting only as agent or custodian, with no ownership rights of its own, giving "XYZ Brokerage as Custodian for Customers" as the model. Where several investors share one CD, the broker will not list each name in the title, and the SEC notes this "may make it harder for you to submit an FDIC insurance claim" if the bank fails.
The third question is aggregation. Federal deposit insurance is $250,000 per depositor, per insured bank, for each account ownership category, and the FDIC notes the limit "includes the principal and accrued interest". A deposit broker may place money at a bank where the customer already holds deposits. If the brokered CD pushes the total in that ownership category at that bank above the limit, the excess is uninsured, which is a risk created purely by where the broker chose to place the money.
The fourth question is how you get out, and this is where a brokered CD behaves least like a bank CD. Brokered CDs generally do not carry an early withdrawal penalty. Instead of surrendering the deposit to the issuing bank, the holder normally sells it on a secondary market, and the price moves with prevailing rates. If rates have risen since purchase, a lower-yielding CD fetches less than face value and the loss is a market loss rather than a penalty. If rates have fallen, it may sell at a profit. The deposit broker may also charge a sales fee to execute that trade, which the SEC says can reduce the return or increase the loss.
The important qualification is one that a page describing only the mechanism would leave out. The SEC prints it as an "IMPORTANT" note: brokered CDs "can generally be sold at any time through a secondary market", but "depending on market conditions, some brokered CDs may not have a secondary market. This will require you to hold the CD until it matures, is called (if possible), or market conditions change to allow for a secondary market sale." A CD that cannot be sold and cannot be surrendered is simply illiquid until its maturity date, and maturity dates on brokered CDs run as long as thirty years.
Interest is usually simple, not compound, and that quietly changes the comparison. A bank CD typically lets interest accumulate and compound inside the account. A brokered CD generally pays interest out to the holder in cash at a set interval, monthly, quarterly or semiannually, so earning anything on those payments requires reinvesting them somewhere else. Two CDs quoting the same rate therefore do not produce the same amount of money over a multi-year term. Many brokered CDs also carry call features, which let the issuing bank end the CD early on its own terms and are covered under callable CDs.