The only way Vanguard could make its 46 exchange-traded funds more attractive is to cover them in chocolate syrup and whipped cream.

The company's ETFs are already super cheap. Now, it's offering commission-free transactions on those funds. For all other ETFs and stocks, commissions will be between $2 and $7, reports ETF Trends.

Low fees have served Vanguard well. The company is now the third-largest ETF provider in the world, with an average ETF expense ratio of 0.52%, reports ETF Trends. And now, Vanguard has the largest group of ETFs available for commission-free trading, writes IndexUniverse.

Normally, investors have to pay a commission every time they trade an ETF, which IndexUniverse said makes it hard to use them for dollar-cost averaging. Removing those commissions now makes dollar-cost averaging possible.

The latest move by Vanguard comes after competitors have offered similar deals. Charles Schwab (SCHW) and Fidelity offer some commission-free ETFs and some that cost less than $10 to trade.

"Vanguard’s lowered brokerage commissions represent an all-out fight for self-directed ETF investor assets -- not just people who use Vanguard ETFs," writes Tom Lydon for ETF Trends.

Dave Nadig at IndexUniverse wonders who exactly is going to end up footing the bill for Vanguard's "free" ETFs. Those trades are still going to cost Vanguard money, after all.

For Schwab, the company's shareholders pay, with the hope that Schwab will get more assets under management as a result, Nadig writes.

But Vanguard's own investors will cover the cost of the ETF commissions because Vanguard is literally owned by its fund shareholders, Nadig writes.

"So that means every shareholder of VWO just became a kind of health insurance company, covering the bad behavior of Vanguard brokerage customers on the back of their buy-and-hold investments," he adds.

Vanguard, for its part, says that it saved tens of millions of dollars internalizing its brokerage operations last year, and can afford to slash fees on ETFs now, writes Matt Hougan.

To see the complete lineup of Vanguard ETFs, click here.

Related reading:

• Can Charles Schwab learn from E-Trade's flubs?
• An ETF revolution: Free trades
• Fidelity cuts commissions to draw investors