BUZZ-Renishaw: best day in 2.5 months after update

** British precision engineer Renishaw (Other OTC: RNSHF - news) up c7 pct and top gainer on the FTSE 250 index in robust volume

** Co cuts FY rev forecast but keeps PBT forecast, causing Investec (LSE: INVP.L - news) analyst Michael Blogg to say that "margins must be better"

** Margins a closely-watched metric for industrials as bottom-line generally represents only a fraction of the top-line number due to huge operating expenses

** Co cites difficulty in predicting large orders this year for rev cut; Its large order wins in the past linked to the launch of new products from Apple Inc (LSE: 0R2V.L - news)

** Strength of the global smartphone market called into question this year, with companies hinting at weaker demand particularly from China

** Renishaw's stock has lost c.5 pct in value since July 28, the day before it first forecast lower FY revenue

** About 6X 30-day avg volume traded through in 5.5 hrs (RM (LSE: RM.L - news) : esha.vaish.thomsonreuters.com@reuters.net)