Speaking at a conference in London on Wednesday (June 30th), Mr Lucas told analysts the bank experienced "softer" market conditions in May and June.
He pointed to lower levels of capital markets business and a decline in advisory work on mergers and acquisitions as two major areas of weakness, according to Bloomberg.
"The conditions are certainly softer than we saw in the first quarter," Mr Lucas commented.
Meanwhile, Barclays has announced a plan to expand its retail banking operations in the UK and Europe, with Â£1 billion to be spent on improvements such as branch overhauls and technology over the next four years.
Spokesperson Perry Jones said the bank will aim to add between three and four million customers to its existing 37 million consumer banking clients by the end of 2013.
By Gary Cooper