The third-largest US lender beat profit estimates but reported a decline in interest margins, with its shares marginally lower in volatile trading.
The sequential squeeze on Citi's net interest margins by 5 basis points is a cause for worry for investors in other large banks, said Marty Mosby, director of bank and equity strategies at Vining Sparks in Memphis, Tennessee. It raises concerns over expected declines in short-term interest rates when the Federal Reserve begins to cut rates, he added.
JPMorgan Chase & Co, Goldman Sachs Group Inc and Wells Fargo slipped ahead of their earnings reports on Tuesday.
The bank stocks fell 0.67pc, while the S&P 500 financial index declined 0.41pc.
Keeping losses in check were technology stocks, with Apple Inc and Broadcom Inc advancing.
The S&P technology index rose 0.2pc, one of the four major S&P sectors trading higher. Second-quarter earnings season start in earnest this week and analysts expect S&P 500 companies to report a 0.3pc year-over-year fall in profit, the first quarterly drop in three years, according to Refinitiv IBES data.
At 11:29 a.m. ET, the Dow Jones Industrial Average was down 10.26 points, or 0.04pc, at 27,321.77, and the S&P 500 was down 1.44 points, or 0.05pc, at 3,012.33. The Nasdaq Composite was up 3.43 points, or 0.04pc, at 8,247.58.
Wall Street notched up record highs last week on heightened expectations of an interest rate cut later this month following Fed Chairman Jerome Powell's dovish comments.
Weighing heavily on the S&P 500 and the Dow Industrials were shares of Boeing Co, which fell 1.1pc on a report that the 737 Max jet may stay grounded until early 2020.
Symantec Corp tumbled 13.2pc and was the top loser on the benchmark index after a report that the cybersecurity company and chipmaker Broadcom have ceased deal talks. Broadcom rose 1.6pc.
General Electric Co fell 1.1pc after brokerage UBS downgraded shares of the industrial conglomerate to "neutral" from "buy".
Paper packaging companies Westrock Co, Packaging Corp of America and International Paper Co shed between 1.6pc and 3.5pc after KeyBanc downgraded their shares, citing risks from a further fall in containerboard and pulp prices.
Declining issues outnumbered advancers for a 1.12-to-1 ratio on the NYSE and for a 1.29-to-1 ratio on the Nasdaq.
The S&P index recorded 60 new 52-week highs and one new low, while the Nasdaq recorded 60 new highs and 39 new lows.