Follow the steps in each example to determine if the acronym or abbreviation needs to use periods.

1. The Securities Exchange Commission (SEC/S.E.C.) has instituted some measures to prevent insider trading.

   Step 1. The source of the abbreviation is "Securities Exchange Commission."
   Step 2. SEC is an abbreviation based on initial letters; therefore, periods are not needed.

2. Prices on the New York Stock Exchange (N.Y.S.E./NYSE) have been dropping steadily due to consumer distrust of company executives.

   Step 1. The source of the abbreviation is "New York Stock Exchange."
   Step 2. NYSE is an abbreviation based on initial letters; therefore, periods should not be used.

3. A recent special report on Cable Network News (C.N.N./CNN) told of additional insider trading that has just been discovered.

   Step 1. The source of the abbreviation is "Cable Network News."
   Step 2. CNN does not need periods because it is an abbreviation based on initial letters.

4. According to economist Jane Featherstone, Ph.D./PhD, the long-term effects on the stock market could be devastating.

   Step 1. The source of the abbreviation is "Doctor of Philosophy."
   Step 2. Use periods since the abbreviation stands for an academic degree.

5. This is not a good time for a company to release an initial public offering (IPO/I.P.O.).

   Step 1. The source of the abbreviation is "initial public offering."
   Step 2. IPO is an abbreviation based on initial letters; therefore, periods should not be used.