Which component is NOT included in operating income?

Operating income is derived from a company's core business operations, reflecting its profitability from regular business activities. It typically includes the revenues generated from sales and the expenses directly associated with producing those sales, which are categorized as operating expenses.

Sales revenue is a fundamental part of calculating operating income, as it represents the income earned from the primary operations of the business. Cost of goods sold (COGS) is also essential since it accounts for the direct costs attributable to the production of the goods sold by the company. Selling expenses are considered operating expenses and include costs related to marketing and selling products.

In contrast, interest income arises from activities outside of the company's primary business operations, such as investments and other financial activities. This type of income is not included in operating income because it does not stem from the company's main line of business. Instead, it is reported as a non-operating income item in the financial statements, usually under other income or in a separate section of the income statement. This distinction helps analysts and investors assess the performance of the company's core operations separately from its financial activities.