J.P. Morgan enhanced its reputation among U.S. institutional investors by standing by its fixed-income clients during the worst of the global credit crisis, according to new research from Greenwich Associates.

Greenwich says that Lehman Brothers and Banc of America were also recognized for their support of clients. Among the most active institutions, Lehman Brothers and J.P. Morgan tie as leaders in providing their clients with the highest levels of support.

In terms of market share, Lehman Brothers holds a slight advantage over J.P. Morgan, which in turn maintains a wide and growing lead over its nearest competitors Deutsche Bank, Goldman Sachs and Credit Suisse, the firm added. J.P. Morgan and Lehman Brothers are also in a dead heat at the top of the industry when it comes to institutions’ ratings of the quality of their fixed-income service and capabilities.

However, the firm noted that the events of the past 12 months have altered the way individual fixed-income dealers are viewed by their institutional clients. “As institutions think about allocating their future fixed-income trading volumes, they are asking, ‘Who stepped up for us last year?’ ‘Who consistently made two-way markets?’ and ‘Who was willing to pick up the phone?’” says Greenwich Associates consultant Tim Sangston. “While it remains to be seen how the performance of individual dealers throughout the ongoing credit crisis will affect this picture over the long term, the firms will not have to wait long to find out what immediate impact the events of the past year have had on their client relationships.”

Greenwich says that J.P. Morgan emerged from the stormy 2007-2008 period with the strongest reputation among all U.S. fixed-income investors while Lehman Brothers and J.P. Morgan tie in “relationship capital” among the most active accounts.

These conclusions are based on assessments from the more than 1,200 institutions participating in Greenwich Associates’ annual research program. Institutions were asked to rate their dealers in a list of categories including supportiveness during the credit crisis, understanding of investor needs, and treatment of sensitive trading information. Based on these responses, Greenwich Associates compiled an overall reputational score for each of the major brokers, which it calls “relationship capital”.

J.P. Morgan ranks at the top of the US market in terms of “relationship capital”, receiving the highest scores from institutional clients for its supportiveness during market turmoil and its broad understanding of buy-side needs. Close behind are Lehman Brothers and Banc of America; both dealers receive strong ratings for supportiveness during the crisis and the two firms tie for first place in terms of institutions’ willingness to share sensitive trading information, it reported.

“Also notable is the performance of two firms outside the traditional bulge bracket — Barclays Capital and RBS Greenwich Capital — which receive Relationship Capital scores matching or even beating those of some large U.S. fixed-income dealers,” says Greenwich Associates consultant Woody Canaday.

The firm points out that the composition of this market changed overnight with the collapse of Bear Stearns earlier this year. Although the firm did not rank in the top 10 in terms of overall U.S. fixed-income trading market share, 36% of U.S. institutions were trading with Bear Stearns as recently as 2007. “While it is far too early to predict how the integration of the Bear Stearns franchise will ultimately play out for J.P. Morgan, it is safe to assume that the firm will get at least some lift in its current battle with Lehman Brothers for the title of the top U.S. fixed-income dealer,” says Greenwich Associates consultant Frank Feenstra.