THE FTSE 100 shed 1.8 per cent yesterday, dragged back by weakness in banks and commodity issues, fuelling doubts over the sustainability of this summer&rsquo;s strong rally.<br /><br />At the close, the FTSE 100 was 89.20 points lower at 4,819.70 after ending 0.8 per cent higher on Friday, when it also touched a near 11-month high.<br /><br />&ldquo;The overriding concern of this recent rally has been its lack of volume and today may have marked the first round of sustained profit taking,&rdquo; said Angus Campbell, head of sales at Capital Spreads.<br /><br />&ldquo;In the back of many investors&rsquo; minds is the concern that September is usually a poor month for equities and we haven&rsquo;t got the month off to the best of starts.&rdquo;<br /><br />Cyclical stocks, more sensitive to resurfacing fears over the global recovery were weaker as a sharp sell-off by global equities on Monday, when London markets were closed for a public holiday, filtered through to the UK market.<br /><br />Banks were the biggest drag on the index, with <strong>HSBC, Lloyds Banking Group, Barclays, Royal Bank of Scotland</strong> and <strong>Standard Chartered</strong> losing between 1.9 and 4.8 per cent.<br /><br />Also among weak financials, <strong>RSA Insurance</strong> shed 4.8 per cent as a report of a rights issue to raise up to $1bn (&pound;600m) unsettled investors and surprised analysts, who said they saw no need for a cash call.<br /><br />Peers <strong>Legal &amp; General</strong> and <strong>Prudential</strong> fell 3.3 and 2.1 per cent respectively.<br /><br />Weak data reinforced the more negative tone at the start of the month, with the manufacturing sector dipping unexpectedly in August and net lending falling at its sharpest rate since records began in 1993.<br /><br />US blue chips were 1.7 percent lower by London&rsquo;s close as an early rally following some upbeat data was reversed as financials took a tumble.<br /><br />Commodity issues were hit by softer metal and crude prices as demand concerns re-emerged with global recovery worries.<br /><br /><strong>Eurasian Natural Resources, Vedanta Resources, Lonmin, Anglo American, Xstrata</strong> and <strong>Antofagasta</strong> fell 4.0 to 6.9 per cent.<br /><br /><strong>BP, Royal Dutch Shell, BG Group, Cairn Energy</strong> and <strong>Tullow Oil</strong> lost 1.4 to 3.9 per cent.<br /><br />Pharmaceuticals stocks added the most points, mainly thanks to good gains from <strong>AstraZeneca</strong>, up 0.6 per cent, lifted by trial results for its experimental blood thinner Brilinta.<br /><br />Peer <strong>Shire</strong> gained 0.1 per cent.<br /><br />Household products, beverage and tobacco stocks were also in demand as investors homed in on stocks they expect to hold firm in a still-challenging economic environment.<br /><br /><strong>Reckitt Benckiser</strong> was the top FTSE 100 riser, up 1.0 per cent, while <strong>Diageo</strong> took on 0.9 per cent, and <strong>British American Tobacco</strong> gained 0.8 per cent.<br /><br />&ldquo;Investors will take a long hard look at the rally over August, and when we see a move back to risk aversion, there&rsquo;s a move back into defensives,&rdquo; said Richard Hunter, head of equities at Hargreaves Lansdown.