There is normally a difference, or spread, between the bid price (the highest price a buyer is willing to pay for a share) and the ask price (the lowest price a seller is willing to accept for a share). The amount of the spread varies from one ETF to another, and tends to be greater for ETFs with low trading volume.

If you plan to hold an ETF for less than a year, this cost can matter more than the OER.
 

The ongoing management fee charged for an ETF by the fund's sponsor. This can vary widely, with the industry asset-weighted average** OER for passively managed ETFs being 0.21%³.

The asset-weighted average OER for cap weighted Schwab ETFs*** is just 0.05%.⁴

You'll typically pay a commission each time you buy or sell an ETF at your brokerage company, but not always. Keep in mind, the smaller your investment and the more frequently you trade, the more impact these commissions will have on your bottom line. Standard trades at Schwab are $0 per trade online.¹

Some fixed income securities have preferential tax treatment where coupon payments may be exempt from federal and state income taxes. 

Keep in mind that potential tax advantages are generally factored into the price of any bond (and therefore its yield). Schwab recommends consulting a qualified tax advisor for specific individualized tax advice.

Fixed income securities are typically designed to provide a regular, predictable stream of interest payments on set dates. Keep in mind that there is a risk that the issuer will not make good on the promise to pay interest income.

Fixed income securities are ideal when preservation of capital is a priority. Specifically with bonds, principal is usually returned at a set maturity date. Higher-quality fixed income investments, like Treasuries, have the best potential for protecting principal. Though preserving capital is a key feature of fixed income securities, there is still the risk that the issuer of the bond will not make good on paying back the principal.

Fixed income securities, specifically high-credit-quality bonds, can help smooth out the highs and lows in a stock portfolio. That's because stock and bond prices have historically tended to move independently and with different magnitudes at any given time. However, diversifying with bonds does not ensure a profit and does not protect against a loss in a declining market.