Recent stock price swings have left many people bewildered. Add in a weakening economy and a crisis on Wall Street and it's fair to say that anxiety has taken over for many investors.

Instead of panicking, it's a good time to revisit some old financial beliefs, says Garrett Gunderson, author of the recently released "Killing Sacred Cows: Overcoming the Financial Myths that are Destroying Your Prosperity."

Many advisers and investors have clung to these notions to guide their investment decisions, but they may hurt more than help, Gunderson says. Here are 10 credos that he thinks investors should reject if they want to build wealth in a market meltdown.