WALL Street is giving Barack Obama the cold shoulder, donating bigger sums to the election campaign of his Republican rival Mitt Romney, while watching warily as the President sides with protesters campaigning against inequality and corporate excess.

Rank-and-file employees of big investment banks, hedge funds and private equity firms are giving substantially less to the President's re-election campaign than they did in 2008, according to a New York Times study, with donations to the Romney camp outpacing those to Mr Obama five to one.

US President Barack Obama and First Lady Michelle Obama walk through the 'Mountain of Despair' at the dedication of the Martin Luther King Jr. Memorial. Credit:AFP Photo

In recent months, Wall Street donors funnelled more than $US1.5 million ($A1.45 million) to Mr Romney compared with $US270,000 to the President, although the Obama campaign continues to reap millions of dollars from other backers.

Evidence that Wall Street's discontent is resulting in a pull-back in financial support for Mr Obama, who has criticised executive bonuses and imposed new regulations, came as he sought to draw a parallel between the struggles of slain civil rights leader Martin Luther King and contemporary injustices, including charges of inequality levelled by the Occupy Wall Street protesters.