I've said it many times on these boards and on TMF. When something goes up a lot in a short space of time, more often then not it is worth selling up and finding the next share that is likely to go up a lot in a short space of time. This principle held true for Dana back in 2008 when it went to £20 on the back of the Rinnes discovery. It went up from £12 to £20 in a matter of weeks, at the time on TMF I was saying Dana got ahead of itself. In fact it never got back to £20 & got taken over.
Rockhopper (LON:RKH) went from approx 50p to £5 in the space of 6 months and now down to about £2.30.
Xcite Energy (LON:XEL) from 50p to £4 in 4 months & now back to £2.40
Caza (LON:CAZA) from 4.5p to 67p in 6 months.
Red Rock (LON:RRR) 6p to 16p in one month and now back to 8p.
Sterling Resources $2 to $4.5 in 6 months & now back to $2.75.
Encore from 15p to 150p in 9 months & back to 95p
Heritage from £1.8- to £6 in 9 months & back to £2.50
It also held true for SOCO International (LON:SIA) when it went from £3 to £6 in 9 months back in 2007.
I can find countless examples of situations where something has gone up a lot in a short space of time and a year or two later it has dropped back.. And pretty much in all those situations you have the same crowd & 'experts' telling you it is going much much higher and have blue sky valuations and all that nonsense.
Sure you won't get that ASOS (LON:ASC) by following Isaac's rule, but an Asos is perhaps one in a billion whereas a drop back like the above is very common. It is not easy to sell up when everyone else around is bullish because it is more comfortable to sit in the same boat with the herd. And I think it is at this point where reading bulletin boards can be costly.