Complex sentence: The typical CEO contract is only three years, so its cutting short costs the CEO little, and only 2% of firms in the S&P 500 would reduce any part of the severance package once the executive finds another employer.
Split into simpler sentences: The typical CEO contract is only three years, so the cost of having its term cutting short costs the CEO relatively little. Furthermore only 2% of firms in the S&P 500 reduce any part of the severance package once the executive finds another employer.