An accounting system developed by Standard & PoorÂ’s (S&P) that attempts to clarify corporate accounting for a companyÂ’s income from day-to-day operations. To arrive at core earnings, S&P calculates the cost of stock options and gains or losses from pension plans and deducts them from corporate earnings. Also subtracted are one-time gains or losses. Under current accounting rules of the Financial Accounting Standards Board, companies arenÂ’t required to deduct the cost of options, but can include gains from pension funds.