This article on investopedia ( http://www.investopedia.com/news/repeat-after-me-valuation-not-catalyst/ ) is a useful reminder that high valuation metrics (eg the US share market is approaching the high valuations US shares had immediately before the 1929 crash) do not tell you that the market is about to crash. Rather, high valuations (on a historic basis) are a warning to pay close attention to technical indicators so try to detect a market down-turn. i.e. High valuations tell you that you need to be extra vigilant.
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