Vanguard recently executed its largest cut to investment fees in its roughly five-decade existence. The largest investment management firm in the world lowered the expense ratio on 168 of its mutual funds and exchange-traded funds (ETFs).

Retirees looking to diversify into international stocks can find a low-cost solution aboard the ship of Vanguard. To this day, Vanguard continues to drive down fees (think gross expense ratios) toward the floor.

Vanguard’s new fee cuts are a win for retail investors — helping to boost long-term returns. Here's what a low expense ratio means.