According to research by Thomson Financial, Sidley has maintained the top spot for advising issuers on international debt deals, as ranked by deal size. The Chicago-based firm stormed ahead of its competitors, advising on 253 deals worth a total of $216.67bn (£110.66bn), representing the largest market share at 5.6 per cent.
Magic circle firms Allen & Overy (A&O) and Clifford Chance bagged second and third places respectively, between them advising the issuers on 294 deals accumulatively worth $239.71bn (£122.43bn).
Fellow magic circle firm Linklaters acted on 176 deals worth $78.02bn (£39.85bn), claiming fifth position, with US firm Sullivan & Cromwell creeping in ahead to fourth place, having acted on 69 deals worth $83.7bn (£42.75bn). Davis Polk & Wardwell, meanwhile, advised on 54 deals worth $51.68bn (£26.39bn), which saw the firm land sixth place in the rankings.
On the manager side, however, it was a trio of magic circle firms - A&O, Linklaters and Clifford Chance - that led the way, boasting a combined market share of 24.1 per cent. A&O held onto the top spot from last year, featuring on 693 deals worth $371.63bn (£189.82bn). Notable deals from last year include the firm advising BAA in connection with its multi-tranche e3bn (£1.97bn) offering and representing HBOS on the first US dollar-denominated covered bond issue, worth $2bn (£1.02bn).
Linklaters closely followed its rival having acted on 549 deals worth $283.33bn (£144.71bn), while Clifford Chance acted on 357 deals worth $279.96bn (£142.99bn).
A&O capital markets partner Boyan Wells told The Lawyer: "US firms tend to concentrate more on equity-related and high-yield work. It's the underwriters that firms need to be close to. Their relationships with London firms run deep and it would be quite a challenge for US firms to break into this."
German firm Hengeler Mueller was the only non-UK or US firm to feature in the top 15 firms acting for the manager on international debt work, having bagged 190 deals worth $87.98bn (£44.93bn), claiming a market share of 2.3 per cent.
But the magic circle firms seem to be losing out to their US competitors when it comes to international high-yield corporate debt work, with Freshfields Bruckhaus Deringer and A&O being the only two magic circle firms to feature in this category of rankings.
Freshfields came in at eighth place advising the issuer, down two places from last year's rankings, having acted on five deals worth $3.45bn (£1.76bn). Simpson Thacher & Bartlett, meanwhile, remained at the top of the chart from last year, having advised on 13 deals worth $17.27bn (£8.82bn).
On the manager side, A&O acted on six deals worth $2.92bn (£1.49bn), climbing up one spot to bag seventh place in the chart, while Cahill Gordon & Reindel retained the top spot advising the manager, having featured on 27 deals worth $18.88bn (£9.65bn).