CMS has seen its share of the listed company market more than double this quarter, catapulting the firm into joint third place with Herbert Smith Freehills (HSF), following its merger with Nabarro and Olswang.

The rankings, compiled by Adviser Rankings in association with audit and advisory firm Crowe Clark Whitehill, also place Slaughter and May at the top of the tables for total number of stockmarket clients, FTSE 250 clients and FTSE 100 clients.

CMS, whose three-way merger went live on 1 May, now has 97 stockmarket clients, up from 38 in Q1 when it was ranked 24th.

The firm also jumped up eight places in the FTSE 250 table during the period, moving from 14th place in Q1 to sixth place. During that time, the firm has increased its total FTSE 250 clients by 10. In the FTSE 100 ranking, it has risen to 10th place, up from 12th, by adding two clients: Land Securities from legacy Nabarro and ITV from legacy Olswang.

CMS corporate partner Alasdair Steele, formerly at Nabarro, said: "The merger has brought us more depth on the issuer side, from both CMS and Olswang, which is what we're seeing in the rankings and across the sectors. Historically, Nabarro was strong on the investment bank side.

"We are now all thinking about what we can take to existing and new clients and what we can go out to market with to get people's attention."

In addition, CMS has entered the Aim market ranking for the first time with 40 clients, the bulk of which belong to legacy Olswang and Nabarro. The combined firm's Aim clients include advertising company M&A Saatchi, internet-based market research company YouGov, real estate agency M Winkworth and oil and gas company Gulfsand Petroleum.

Meanwhile, Slaughters has retained the top spot with 106 stockmarket clients, gaining one new client, while Pinsent Masons remains in second place with 98 clients, up from 96.

Slaughters also topped the FTSE 250 and FTSE 100 rankings with 35 and 33 clients respectively.

The magic circle firm's M&A head Roland Turnill said: "In terms of our position in the rankings, it is of course encouraging to see validation of the time and effort we put into building relationships and giving our clients and potential clients what they need."

Commenting on market conditions, Turnill added: "Since news of the UK election, there's been a tailing off in activity. Everyone is waiting to see what happens. For M&A, there are two issues. First, assuming Theresa May wins, what's the size of her majority and what will she do with it – particularly in terms of industrial strategy and the mooted changes to the takeover regime? Secondly, how will the Brexit talks begin?"

Other magic circle firms with top spots in the FTSE 100 table include Allen & Overy in second place with a total of 27 clients, Linklaters in third (25) and Freshfields Bruckhaus Deringer in fourth (23).

In the FTSE 250 category, Linklaters is in second place with 32 clients, while HSF has placed third with 30 clients.

During the quarter, Linklaters gained three FTSE 250 clients – outsourcing company Capita, electronics retailer Dixons Carphone and online food delivery service Just Eat. It lost one: betting company CMC markets.

HSF also gained three: Capita, retail bank Aldermore Group and specialty chemicals business Elementis.