A pair of Am Law 100 firms made their way to the top of three separate rankings of M&A legal advisers for 2014′s first quarter, thanks largely to their roles on two of the largest transactions announced so far this year.

Skadden, Arps, Slate, Meagher & Flom and Simpson Thacher & Bartlett ranked as the top two firms, in varying order, in the first-quarter league tables released this week by Bloomberg, Mergermarket and Thomson Reuters. The three outlets track trends in the M&A market and their latest reports rank law firms on the total value of their corporate clients’ global transactions in the first three months of the year. Skadden topped the rankings released by Bloomberg and Thomson Reuters, finishing just ahead of Simpson Thacher. The results were flipped in the Mergermarket rankings, with Simpson Thacher taking the lead. White & Case rounded out the top three slots on all three lists.

As The Am Law Daily has reported in the past, the three outlets rely on different criteria when compiling their rankings, making the league tables primarily useful as a broad guide to which law firms are most active in the M&A market in a given period.

Of the top three firms this year’s first quarter, only Simpson Thacher earned the same distinction on any of the three outlets’ January rankings covering all of 2013. That was largely the result of the firm’s role advising Vodafone on the $130 billion sale of its 45 percent stake in Verizon Wireless to Verizon Communications—one of the largest M&A transactions in U.S. history.

Simpson Thacher and Skadden both kicked off 2014 by advising on two of the most substantial deals announced so far this year: Comcast’s $67 billion purchase of Time Warner Cable, and the $25 billion sale of Forest Laboratories to generic drug maker Actavis. Neither firm served as the sole lead legal counsel for the companies involved in those transactions. Time Warner Cable was advised on its February sale by a team of Paul, Weiss, Rifkind, Wharton & Garrison attorneys, with Skadden also advising the cable company. Later that month, Skadden was enlisted by Actavis as antitrust counsel on its purchase of Forest. In both deals, Simpson Thacher landed roles representing the financial advisers to primary players Comcast and Forest, respectively.

(Davis Polk & Wardwell, which took the lead role for Comcast on the Time Warner deal, placed fourth in all three outlets’ rankings; Paul Weiss ranked either sixth or seventh, depending on the ranking.)

The Forest and Time Warner sales bolstered a notably active first quarter for M&A deals. Mergermarket notes in its report that global M&A volume during this year’s first three months was up 33.2 percent, to $599.1 billion, compared with the same period last year.

The three outlets also ranked law firms on the total number of deals announced by clients during the year’s first three months. Jones Day and Kirkland & Ellis traded off the top spot, with the former topping both the Bloomberg and Thomson Reuters rankings, and the latter outpaced its Am Law 100 rival on the Mergermarket list.