Before the stock market opened on July 15 Citigroup (C) reported a 21%  earnings per share increase in second quarter above the comparable 2010  quarter . Its stock surged $1.37 or 3.5% at the opening to $40.39 .   This rise in price was accompanied by heavy volume and seemed to offer a  glimmer of hope to long suffering shareholders.  By noon, however,  Citigroup (C) had lost all its gains. During the afternoon (C) fell as  low as $38.12 before ultimately finishing the day off $0.64 or 1.64% at  $38.38.
The dispiriting price action for Citigroup was  accompanied by price declines in JP Morgan Chase (JPM), Bank of America  (BAC) and Wells Fargo (WFC).  The percentage decline at (C) was greater  than at these other large banks.
It seems clear that in the  current environment market participants will always be able to find  something disturbing with bank financials that will outweigh any  improvements cited by management.  In the case of Citi the decline in  net interest margin (NIM) to 2.82% in the second quarter of 2011 from  2.88% the previous quarter was particulary unwelcome news.  During the  second quarter of 2010 Citi had reported a NIM of 3.15%; therefore, NIM  declined by 33 basis points or 10.5% in one year.  Wall Street hates  declines in margins and has a long history of punishing companies and/or  industries that experience such declines.
An examination of the  decline in net interest margin at Citi reveals it was largely  attributable to a very pronounced decline in the yield on its investment  portfolio.  The yield on that portfolio was 2.79% during the quarter  just ended, while it was 3.17% during the first quarter of 2011 and  3.89% during the second quarter of 2010.  This is a remarkable and  worrisome decline in yield on an investment portfolio that averaged $318  billion during the second quarter of 2011, $320 billion in the prior  quarter and $311 billion during the second quarter of 2010.
Adding  further selling pressure to (C) was the fact that  Citigroup increased  its staff by 2% or 3,000 people during the second quarter.  The fact  that it increased staff while margins were under pressure is a source of  concern even though its total staff is the same as it was the year  before. Investors generally expect payroll reductions, not additions,  when margins are under pressure.
On a positive note it should be  mentioned that loans outstanding rose slightly in the second quarter  versus the prior quarter and the average loan yield rose 13 basis points  to 7.93%.  Loans outstanding still remain well below the level of the  prior year.
The positive impact that would result from  redeploying funds from investments yielding 2.79% and deposits with  other banks yielding 1.06% into quality loans yielding 7.93% is obvious.   Citi needs to accelerate its lending if it expects to meaningfully  increase its income by reversing the decline in its net interest margin,  and it must do so without compromising credit quality.  If its lending  staff cannot generate quality loans then Citi will have to start  acquiring fixed and floating rate corporate obligations with the ample  funds it currently has available.
Disclosure: I am long C