I'm thinking that continuing to hold my long position in Aberdeen New Thai investment trust is likely to result in a negative surprise at some point very soon?

"What do you think?"

David Fuller's view Well done for not only holding this position but also for your timely question.

I agree with you. ANW shows a Type-1 ending as taught at The Chart Seminar, in the form of a climactic acceleration following a ranging upward trend since late-October 2008. This is an ending signal although ANW has yet to break downwards. The move is partly influenced by sterling's weakness against the Thai Baht - THB/GBP, which also looks somewhat overextended. More importantly, Thailand's SET Index is also overstretched relative to its MA.

Tactically, your decision is whether to stand aside now, or to introduce a trailing stop. Personally, I would not worry too much about the possibility of selling too soon when a long uptrend shows a clear overextension in the form of Type-1 acceleration.