Corporate M&A Path to Partner: Fast Track, Thin Pipeline

Sartori & Partners data give a short answer to how long to make partner in M&A: a median of 9.0 years from the first year of practice, against 10.0 years across all practices, measured on 1,990 corporate promotions over the last 5 years. The harder number for a firm sits elsewhere. Since May 2026, corporate and M&A lawyers moving to companies have equaled 20.1% of the practice's lateral moves, against 13.1% for the whole market. A practice that promotes early needs a deep bench of senior associates to promote from, and corporate is where that bench leaks most visibly to in-house roles.

In the 6 months to October 2026, 316 corporate and M&A lawyers left law firms for companies. Set against the practice's lateral moves in the same months, that equals 20.1%, 1.5 times the rate across all practices. The other large practices sit near the market line: litigation at 12.3%, banking and finance at 12.7% and private equity at 11.4%. Corporate lawyers make up 33.2% of all moves from firms to companies, second only to litigation. Moves in-house are tracked in full only from May 2026, so there is no earlier year to set this against.

The drain falls on the people a firm would promote. Across all practices, 76.7% of lawyers who moved in-house were associates and 11.0% were partners. Companies recruit corporate associates because deal experience transfers directly to a legal department that buys, sells and finances businesses. For a firm, the consequence is that a corporate class that looks full at mid-level can reach the partnership decision thin, and the gap is then filled by lateral hiring.

The faster track holds across the range, not only at the middle. Corporate partners in the quickest quarter were promoted by 8.0 years, against 9.0 years market-wide. At the slow end, the corporate mark is 11.0 years against 12.0 years. By that later mark, 83.9% of corporate partners had been promoted, against 75.4% across the market, a gap of 8.5 points. The mean tells the same story, 10.2 years against 11.1 years.

These figures count years from the first year of practice to the promotion, for partners made up in the 5 years to May 2026. Litigation, the largest promoting practice, sits on the market median of 10.0 years. For a firm, the corporate clock is shorter: associates expect the partnership question about 1 year earlier than peers in most practices, and a senior associate without an answer is the one most open to a company's offer.

Speed does not mean self-sufficiency. In the 12 months to May 2026, firms promoted 620 corporate and M&A lawyers to partner, 21.0% of the 2,955 partner promotions across all practices. Set against the lateral partners the practice hired in the same months, that is 0.75 promoted for each lateral partner. The market ratio is 0.79, from 2,955 promotions against 3,749 lateral partner arrivals. Litigation runs at 0.80 and employment and labor at 0.95, so the practices with slower clocks build more of their own partners.

Below parity, a practice adds more partners by hiring than by promotion. For a corporate group, that means the partnership is built partly from outside every year: plan the lateral budget alongside the promotion round, not after it.

The buy side is growing. Sartori & Partners data show corporate partner arrivals went from 778 to 873 in the settled 12 months to September 2026, so they rose 12.2%. Partner moves across all practices rose 8.4% over the same windows. In the latest 12 months, 870 of the practice's lateral moves were partners, 29.9% of the total against 27.7% market-wide.

A rising market for corporate partners means more firms chasing the same candidates. A firm whose own pipeline is thinned by in-house moves will be bidding in that market more often, so the cost of an associate who leaves for a company shows up later as a lateral search.

Private equity is the practice closest to corporate work: 38.2% of corporate movers also practice it. Its partners share the corporate median of 9.0 years, and 86.7% were promoted by the 12.0 years mark. It relies on laterals even more, at 0.68 promoted per lateral partner. The difference is the drain: private equity moves to companies equal 11.4% of its lateral moves, against 20.1% in corporate.

For a firm with both groups, private equity associates are the steadier promotion pool, while corporate associates need the earlier and more explicit partnership conversation.

First, start the partnership conversation earlier. With a corporate median of 9.0 years, the associates a firm most wants to keep are deciding their future a year before peers in litigation, and companies are recruiting from the same group. Second, budget for laterals as a standing line. At 0.75 promoted per lateral partner, the practice cannot fill its partnership from within, and the lateral partner market it buys from rose 12.2% year on year. Third, treat retention of senior associates as part of partner supply. In the Sartori & Partners lateral database, 316 corporate lawyers moved to companies in 6 months, and each one a firm keeps is a lateral search it does not have to run.