US firms have slipped down the league tables for UK M&A activity, with magic circle and UK firms dominating all of the top six slots in 2018 for the first time since 2014.

Kirkland & Ellis, Davis Polk & Wardwell and Skadden Arps Slate Meagher & Flom, which took the top three spots in 2017, all fell in the last 12 months. Kirkland plummeted to 12th, Davis Polk to fourth and Skadden to 9th, according to the data compiled by Mergermarket for Legal Week.

Freshfields Bruckhaus Deringer topped the table for 2018 after advising on 60 deals worth a total of $144.4bn. It was followed by Slaughter and May ($119.6bn), Herbert Smith Freehills ($116.3bn), Clifford Chance ($86.5bn) and Allen & Overy ($83.1bn). Linklaters ($70.9bn) came sixth.

It marks a significant change on the previous three years, in which at least two US-based firms have taken top five rankings.

Freshfields M&A partner Bruce Embley said the activity of particular sectors could influence which firms rank highly.

He added: "Clients might look at using a different firm for big public deals than they would for private equity deals. Within different sectors, you see different firms having particular strengths. Big M&A continues to face more and more hurdles, including protectionist trends. 

"Clients are incredibly sophisticated and want to choose firms that they believe are best placed to navigate these challenges; it may well be that circumstance fed more into the UK-headquartered skillset."

UK M&A deal volume in the last quarter fell to its lowest point since Q1 of 2014, with the sector racking up 333 deals worth $34bn (£26.6bn).

However, the rest of 2018 was busier. Law firms worked on 1,519 deals across the full year worth $245.8bn (£192.6bn) in the UK.

Deal highlights for Freshfields included the second largest M&A deal of the year in Europe – Comcast's purchase of Sky, a deal that also handed roles Davis Polk & Wardwell, A&O, Skadden Arps Slate Meagher & Flom, Simpson Thacher & Bartlett, HSF and Slaughters.

Freshfields also advised opposite Linklaters and A&O on the third-biggest deal of the year, in which energy company E.ON €43bn (£38bn) acquired a controlling stake in renewable energy business Innogy from German rival RWE.

DLA Piper did the most deals in the UK with 128 mandates, with CMS in second place on 125.

Nigel Wellings, co-head of London corporate at CC, said: "We saw a very busy summer. Our cycle is a bell curve where we usually expect to ramp up from September. That whole curve came forward and didn't really stop."

Gavin Davies, global M&A head at HSF, said key drivers of activity were corporates with cash seeking rationalisation and growth, private equity with dry powder needing to invest, and cheap debt.

"These drivers prevailed over the headwinds of political and economic uncertainty, populist protectionist trends creating greater political interest in deals, and high value expectations," he said.

For activity across the whole of Europe, Freshfields topped the M&A tables for the third year in a row with deals worth $343.5bn (£269.2bn). Linklaters came second with $288.3bn (£225.9bn) and A&O jumped from 13th place to third place at $241.1bn (£188.9bn).