Shearman & Sterling and K&L Gates have both posted increased global revenues, becoming the latest US-headquartered law firms to report strong financial performance in 2013.

In London, Shearman saw a 20% revenue increase to $134.8m (£80.9m), the office's fourth straight year of revenue growth against a lawyer headcount rise of 7%. The results mean that since 2009, City revenue has increased 36%.

The London revenue jump accounts for almost a third of the firm's global revenue increase, which grew 9.1% to $820.5m (£492.1m). Lawyer headcount fell 4% to 809, partly as a result of departures when the firm exited from Munich and Duesseldorf in the summer.

There were also notable increases in profit per equity partner (PEP) and revenue per lawyer, with the firm averages up 18.4% to $1.8m (£1.01m) and 13.4% to $1.01m (£606,000) respectively.

Meanwhile the London outpost of K&L Gates saw a 14% revenue jump to £40.5m, up from £35.6m in 2012, despite a 17% drop in partner headcount to 50 last year.

Across the firm, revenue increased 9.3% to $1.16bn (£698m), largely buoyed by the merger with Australian outfit Middletons at the beginning of 2013. However, the firm's profit margin fell slightly to 27.6%.

Net income for fully participating equity partners dropped 7.5% to $832,400 (£499,200), while revenue per lawyer also slipped 5% to $586,800 (£352,000).

For the second year in a row, the firm disclosed a thorough breakdown of its financial performance.

The decision to do so was made by chairman and global managing partner Peter Kalis, in response to the perceived reputational damage to the legal industry incurred by the lack of financial transparency at Dewey & Leboeuf prior to its collapse.

The firm's accounts also mention its intentions to wind up its San Diego office by September 2014, with the four lawyers currently left at the office now in consultation to transfer to K&L's Orange County base.

This week, K&L Gates also promoted 52 lawyers to partner, including four in London.

Regulatory and policy special counsel Christine Braamskamp, technology senior associate Andrew Danson, finance consultant Julian Goodman, and disputes senior associate Frank Thompson were all awarded partnership, which comes into effect 1 March.