Here are the steps to replicate Bollinger Bands in Excel for IBM US Equity:
1. Use the Bloomberg function =BDP() to pull historical closing prices for IBM US Equity into Excel. Specify the date range needed.
2. Calculate a simple moving average (SMA) of the closing prices over a period (typically 20 days). Use the AVERAGE function on a rolling window of prices.
3. Calculate the standard deviation of prices over the same period. Use STDEV.S on a rolling window.
4. Add and subtract twice the standard deviation from step 3 to the SMA from step 2. This gives the upper and lower Bollinger Bands.
5. Plot the closing