This article was provided courtesy of ETFtrends.com

While everyone can just sit back and enjoy the expense ratio cuts as the result of the so-called fee war, investors should still be wary of other costs to trading exchange traded funds.

Expense ratios are not the only costs associated with ETF investments. Bid-ask spreads – the price difference between the buying price and the selling price – and commission fees are just some other factors to consider.

The bid-ask spread is found by taking the bid subtracted from the ask, divided by the share price and multiplying by 100. [Read More: Bid-Ask Spread]

“The ETF expense ratio is an ongoing annual charge, whereas the bid-ask spread and commission costs are at the time of a transaction,” Joel Dickson, senior ETF strategist at Vanguard, said in a Wall Street Journal article.

Michael Iachini, managing director of ETF research for Charles Schwab Investment Advisory Inc., though, has offered a simple formula to convert expense ratios, bid-ask spreads and commission fees to a single per-year percentage expense:

  • First off, the expense ratio remains as a percentage.
  • The per-year, bid-ask spread percentage is calculated by dividing the current spread with the holding period. For instance, if an investor holds a fund for half a year, the spread is divided by 0.5, and if the fund is held for 2 years, divide by 2.
  • Lastly, the commission is taken out whenever you buy or sell a fund, unless the brokerage offers commission free trades. The commission per-year percentage conversion is taken by multiplying the commission fee by 2, divided by the total dollar amount invested and then multiplying by 100.
  • ETF investors can then add up the three numbers to calculate the total annual cost in percent terms.

Since the calculations are based on a time component, the total cost for long-term holders will inevitably be lower than for short-term traders.

Additionally, potential investors should be aware of other implicit costs, like premiums or discounts to underlying holdings, that may hurt or help performance. [Read More: Premiums and Discounts]

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