Cash balance plans have exploded in popularity and now hold more than $1 trillion. of wealth.

I'm Ariana Aspuru for The Wall Street Journal. On top of their 401(k) plans, many lawyers, doctors and accountants also have another retirement savings option. It's called a cash balance plan.

Doctors, lawyers and accountants have 401(k) plans. But many have another retirement-saving weapon. It is called a cash balance plan, and it lets people save up to about $3.6 million on top of a ...