The good times keep rolling for fund investors.

Nearly every type of fund rose last quarter, whether focused on stocks or bonds, U.S. or foreign. Gains were so widespread that more than 7,000 of the roughly 7,600 funds that Morningstar tracks made money over the last three months. The nearly universal climb for funds means many retirement accounts and other portfolios are the largest they've ever been. The average 401(k) balance had already come into the second quarter at a record level, according to Fidelity. [...]

The largest mutual fund by assets, and one that's the centerpiece of many retirement portfolios, closed out its seventh straight quarter of gains. Vanguard's Total Stock Market Index fund returned 3.1 percent for the three months through Thursday.