Ideally you should determine the target price PRIOR to purchasing the share, IF it conforms to your individual risk/return profile. The latter depends on various valuation techniques (PE, relative PE, PEG, discounted cashflows, price to book, price to sales etc.) all subjective, hence the various buyers and sellers of a particular share at a particular price.
Let it run with a 20% stop from its closing price. Whenever it closes higher than the previous high close adjust your selling price. This way u can particpate all the way up to R2 or R3 or whatever price. But if on any day it turns and over a period of time comes of with 20% sell. THat way u still bag a profit, currently of around 20% or so if stop was to kick in.
No slight misunderstanding. Example - ANsys closes at 145. 20% loss on that would be 29c and Ansys trading below 116. If that happens, u sell at 116 and move on. That way u still make 16% return on your initial investment of 100c BUT if Ansys continues to go up, even if it goes down into the 120c u just wait because if it goes to say 180 u do the above calc again and now u will sell when if falls back to 144! It may never fall 20% from its highest close for a very long time and this allows u to participate fully! IMPORTANT - U dont calc the 20% loss on each closing, making it a moving target. U can only adjust that price if it closes higher than the 145 As a second trigger U can decide that once the share price has doubled u only want to work on a 10% loss, so u make your stoploss tighter and u protect more of the upside. this way u dont have to worry over whether 20%, 40% or a 1000% growth is enough, the market will show you when it is enough! hope this explains a little better!