我前阵子刚问过Fidelity,他们说退休账户的钱没有额度限制，全部受保护。其他的个人账户就是SIPC。但投资股票的钱不算Fidelity的，他们等于是个中介，他们倒闭了，股票都还在的啊。不知道国债t-bill是不是更安全

Excess of SIPC 

In addition to SIPC protection, Fidelity provides its brokerage customers with additional "excess of SIPC" coverage. The excess coverage would only be used when SIPC coverage is exhausted. Like SIPC, excess protection does not cover investment losses in customer accounts, including losses due to market fluctuation. For example, fraud claims would not be covered if the brokerage firm was still in operation. Total aggregate excess of SIPC coverage available through Fidelity's excess of SIPC policy is $1 billion. Within Fidelity's excess of SIPC coverage, there is no per customer dollar limit on coverage of securities, but there is a per customer limit of $1.9 million on coverage of cash awaiting investment. This is the maximum excess of SIPC protection currently available in the brokerage industry.

Fidelity's FDIC-Insured Deposit Sweep Program details

In utilizing the Program, your uninvested cash balance is swept to a program bank where the deposit is eligible for FDIC insurance. If you have more than $245,000 in uninvested cash in your account, the Program will maximize your eligibility for FDIC insurance by allocating uninvested cash across multiple program banks. We currently have about 20 banks available for Fidelity Cash Management and IRA accounts (although new deposits at any point in time are subject to bank capacity limits). Assuming all the banks have available capacity, a customer could have up to $5 million of uninvested cash covered by FDIC insurance

你手里的股票又不是券商的，券商倒闭了大盘的股票和债券还在啊？券商就是一个买卖的经纪而已。

这个和银行破产是两回事儿。