That's a substantial jump from the February 2014 report, which offered the firm's first analysis of mobile app transactions. Back then, only five of the 17 total firms (29 percent) offered a transactional app, including four phone apps and one tablet app.

Every firm covered in the current report enables participants to adjust contribution rates from at least one mobile platform. That's the most commonly offered mobile transaction, by a long shot.

No other transaction is available on more than one mobile platform of at least half of the firms covered in the report, and certainly not among the coverage group as a whole.

Half of the firms in the current report provide a mobile fund exchange transaction, 33 percent offer an optimized future investment allocations change transaction and 25 percent provide an optimized rebalance account option.

Among other findings, the report said that 50 percent of the firms it covered enable users to conduct transactions in terms of specific dollar amounts; 50 percent offer quick links to applicable fund information; and 58 percent provide quick links to applicable plan details.

The Principal features a mobile-friendly rollover request process, while Vanguard and T. Rowe Price provide mobile-friendly loan requests.

In addition, the report said, “The firms covered … provide an inconsistent selection of design and help features on the transaction interfaces. While all firms present relevant plan data on at least one transaction interface, such as current contribution rates or holdings details, only 42 percent supplement the data with charts or graphs. Two-thirds of firms offer help options, such as detailed instructions, FAQs or balloon tips.… Only one firm, Merrill Lynch, requires participants to enter their account password in order to submit a transaction from a mobile platform.”

While firms are getting on board regarding mobile transactions, it's apparent from the report that there's still a way to go in providing participants with a consistent and seamless experience.