NEW YORK ( TheStreet) -- Morgan Stanley ( MS) was the loser among large-cap U.S. banks on Monday, with shares sliding 3.4% to close at $27.22. The KBW Bank Index ( I:BKX) was down 1.6% to close at 62.56, with all but one of the 24 index components ending with declines. Shares of Citigroup ( C) were down 3.2% to close at $49.57. Index components ending with losses of over 2.5% included BB&T ( BBT) of Winston-Salem, N.C., closing at $34.19, and JPMorgan Chase ( JPM) which closed at $51.46. The Financial Times on Sunday reported that Citigroup "has suffered a significant decline in trading revenues that threatens to depress its earnings," citing unnamed sources. Investors are expecting a rough third quarter earnings season for several of the largest U.S. banks, with very large declines in mortgage lending revenue being signaled or preannounced by many, as refinancing volume drops. The largest banks are also expected to see a major decline in trading revenue. "July and August were very slow months as investors sat on the sidelines waiting for more clarity on Fed tapering, Syria and the EM slowdown and we believe the weakness has extended into September," Atlantic Equities analyst Richard State wrote in a note to clients Monday morning. Staite on Monday estimated the eight large-cap U.S. banks covered by his firm would as a group see a 20% year-over-year decline in third-quarter fixed-income trading revenue. The analyst cut his third-quarter earnings estimate for Morgan Stanley by 25% to 38 cents a share from 50 cents. Staite also cut his third-quarter EPS estimate for Citigroup by 14% to $1.05 from $1.22, while lowering his third-quarter EPS estimate for Goldman Sachs ( GS) by 18% to $2.47 from $3.00. The analyst had previously cut his third-quarter EPS estimate for JPMorgan Chase by 14% to $1.25. Shares of Goldman Sachs were down 2.7% to close at $165.25.