Citigroup Inc. shares today fell the most in seven months after an article by Bloomberg News put a spotlight on a part of the bank’s financial statements that usually gets little attention.

Tucked near the bottom of Citigroup's balance sheet are $17.1 billion of paper losses that very much count, except for one place where they don’t: The bank’s net income.

The line item is called “accumulated other comprehensive loss” -- a name so awful and devoid of plain-English meaning that the Financial Accounting Standards Board, which sets U.S. accounting rules, deserves a dunce cap for coining it. It includes $10.6 billion of cumulative losses for so-called foreign-currency translation adjustments, $2.2 billion of losses on derivatives that are classified as cash-flow hedges, and $5 billion of red ink related to Citigroup’s pension plans. The figure also includes $766 million of net unrealized gains on certain investment securities.

These gains and losses do get counted in Citigroup’s shareholder equity, which was $193.4 billion as of March 31. They also are included in a broader measurement of profitability known as comprehensive income. They reflect real economic activity and have direct, measurable impacts on the values of the company’s assets and liabilities. There’s no good reason not to include such fluctuations on the company’s income statement.

More than 30 years ago, however, the accounting standards board started down the path of letting companies separate certain items that were perceived to be volatile from the rest of their reported earnings. And so now readers of financial statements have to put up with a hodge-podge approach in which all gains and losses are presented for some purposes as if they were of comparable importance, but for other purposes some amounts are omitted entirely.

Today some Citigroup investors are paying a little more attention to these numbers. The company’s stock fell as much as 4 percent to $49.85 after Bloomberg reported that Charles Peabody, an analyst who leads research at Portales Partners LLC, recommended that investors sell Citigroup shares. Peabody estimates that the bank may lose $5 billion to $7 billion of equity this year if the dollar gains against the yen, euro and emerging-market currencies. If he’s right, this also would hit Citigroup’s regulatory capital.

The accounting standards board recently began requiring companies to give greater prominence to comprehensive income on their financial statements, and this is a good thing. Nonetheless, it seems that some investors still tend to ignore numbers that don’t get included in net income, at least until the point comes when a problem becomes so large that it threatens to bite them. They do so at their own risk. It would be better if the accounting rulemaker got rid of the exclusions altogether.

(Jonathan Weil is a columnist for Bloomberg View. Follow him on Twitter.)