Sell Signal
If price is on a down trend and starts to retrace, then most traders might wait to sell at a better price when the price hits a resistance level. Traders will sometimes use the MA to determine the resistance level.
A sell signal is generated when price hits the MA, turns and starts moving in the downward direction. The signal is confirmed when price closes below the MA. Because many traders use the moving averages to generate trading signals, price will normally react to these levels.
A stop loss should be set just above the MA. Ideally it should be set a few pips above the previous high.
http://www.tradeforextrading.com/index.php/movingaverage/support-resistance-levels