As more law firms create and expand nonequity partnership tiers, some lawyers are raising alarm bells over the impact on women and diverse lawyers' careers.

It's no secret that Big Law partnerships tend to be much less diverse than the ranks of associates. But the split within the partnership tiers also shows a divide. About a third (32%) of Am Law 200 nonequity partners last year were women, while that number drops to less than a quarter (24%) in the equity tier, according to ALM data. And when it comes to racial and ethnic diversity, Am Law 200 firms, on average, have even fewer diverse equity partners (12%).