Today’s column is inspired by a reader who wants to know whether he should split his assets among several brokerage firms to stay below the $500,000 limit set by the Securities Investor Protection Corp. “I am told that investments in financial houses such as Fidelity, Vanguard, etc. are insured up to $500,000. These days it is easy to exceed the amount especially in retirement vehicles,” wrote Jerry Fisher of Menlo Park.