Nearly 2.5million complaints were opened against financial services firms between July and December 2013.
The latest data published by the Financial Conduct Authority represents a fall of 15%.
In terms of investment firms Hargreaves Lansdown Asset Management had the most at 3,173 while Barclays Stockbrokers was second with 1,799.
The most number of complaints about pension companies was against The Prudential Assurance Company which had 6,391 while Friends Life was second with 6,219.
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Overall 2,479,029 new complaints were opened against financial services firms between July and December 2013 compared to the 2,911,154 in the previous six months.
Martin Wheatley, FCA chief executive, said: "No firm wants to top this particular list and they all should be striving to ensure that customers are being treated fairly and not given cause to complain.
"This is an indication that firms seem to be putting customers at the heart of their business, however, there is clearly more for us all to do to show consumers their interests come first."
Decumulation, Life and Pensions
· The Prudential Assurance Company Limited – 6,391
· Friends Life Limited – 6,219
· Phoenix Life Limited – 5,142
· Aviva Life Services UK Limited – 4,458
· The Royal London Mutual Insurance Society Limited – 3,605
Investments
· Hargreaves Lansdown Asset Management Limited – 3,173
· Barclays Stockbrokers Limited – 1,799
· Santander UK Plc – 1,791
· Financial Administration Services Limited – 1,540
· HSBC Bank Plc – 1,480
