Through the summer and throughout the US, Wall Street trading houses - and one firm in particular - have received a polite reminder of what an old boy network their industry used to be.

Small numbers of disgruntled current and former female employees of Merrill Lynch's broking arm have protested regularly outside the firm's offices in several US cities. They are demanding that executives increase the pace at which they are meting out compensation for a 1998 class action lawsuit in which Merrill was alleged to have maintained a long-standing pattern of gender discrimination.