A golden umbrella is a clause in an entrepreneur's contract with their company, typically the CEO or COO, that guarantees a certain payout for the risk they bear in starting the company.
The down-side of a golden umbrella is that angel investors typically do not know the terms of a golden umbrella, thus a CEO may start a company, grow the company, seek first-round and second-round venture capital, and then exit the company with a large pay-out just before the company's market growth takes a downturn due to poor business planning.
References
Golden umbrella Wikipedia(Text) CC BY-SA