The Exchange referred to is the Qatar stock exchange. The inference is that whilst the overall exchange index is falling due to bad performance with falling share prices across most stock sectors on the market, e.g. shipping, insurance, engineering, etc., those stocks/shares in the industrial sector are bucking (or propping up) the market. i.e. performing much better than the overall trend and keeping the overall index higher than it would otherwise be.
Think of a pit prop which supports the roof of mineworkings. i.e. they prop them up.
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