Market report: Ocado benefits from 'anti-supermarket' trade "People are worried about shorting it because it has squeezed so much in the past," he said. Normally what would happen if something went up for no apparent reason is that somebody would come and short it on the basis the rise was unjustified.  Waitrose also reported Christmas trading today, with like-for-like (LFL) sales up 3.1pc in the five weeks ending on Christmas Eve. However, the numbers did not incorporate Waitrose's supply agreement with Ocado and analysts did not think that any read-across from the Waitrose figures would have been enough to lift the online grocer almost 12pc. Ocado publishes its Christmas trading statement next Thursday. The supermarkets were broadly lower in the wake of Sainsbury's update. While not as bad as the market had feared, with LFL sales excluding fuel edging up 0.2pc, Sainsbury's nevertheless unsettled investors by lowering its guidance for full-year sales growth. As a result, the shares fell 8.9, or 2.4pc, to 360p, dragging rival Tesco 3.45 lower to 328.3p. Morrisons lost as much as 2.1pc before recovering to close up 0.6 at 254.2p, a 0.2pc gain. The FTSE 100, of which all three are members, closed 33.67 points lower at 6,721.78. Falls in the cigarette companies weighed on the benchmark index, with Imperial Tobacco off 67p at £22.47 and British American Tobacco 31p cheaper at £31.54½. Reports that China is planning to ban smoking in public spaces were initially blamed for the weakness, although analysts pointed out that neither company has any material Chinese exposure. A Canaccord Genuity downgrade of Imperial to "sell" was more likely to have hurt sentiment, they said. RSA Insurance, 2.95 better at 100.7p, led the blue-chips higher after confirming a Telegraph report that the £200m capital shortfall its Irish arm is believed to be an isolated incident. Berenberg analysts also helped RSA shares, speculating that a bid approach from Aviva, up 6 at 460.2p, was "not without theoretical merit." "Given the overlapping general insurance footprint, an approach for RSA would appear to have considerable industrial logic," they said. With two thirds of RSA's premiums coming from complimentary regions, combining the two operations would establish market leadership positions. Such a scenario would be something of a reverse of 2010, when Aviva knocked back an approach from RSA for its general insurance business. Back with the session's fallers, an article in the trade press raising concerns about corn sweetener pricing hit Tate & Lyle, the maker of the sweetener Splenda, which was the heaviest faller in the FTSE 100, losing 27½ to 773p. International Personal Finance was hit by a downgrade to "sell" at Panmure Gordon and slumped 26 to 484p. IPF tumbled after the festive period when the emerging markets focused lender revealed it was being fined £2.4m by Polish regulators for the way it calculates APR on loans. Even more worryingly, Poland is also considering broader revisions to APR calculations. Of the wider regulatory changes proposed in Poland, Panmure expert Keith Baird said: "The potential impact would be to lower total charges from 90pc to 65pc, or nearly a 30pc fall. Applying that to Polish profits could potentially wipe out most of them and reduce group profits by almost half. He slashed his price target to 400p from 700p. Similarly, Rightmove slid 91p to £27.11 after UBS analyst Catriona O'Grady downgraded the property website group to "neutral" from "buy" on valuation grounds. "We believe the current share price reflects the potential for near-term upgrades to earnings driven by further housing market growth in 2014," she said. UBS also was responsible for lifting engineering software company Aveva 137p higher to £22.61. Shares in the mid-capper tumbled in November when the group posted disappointing first-half results. However, UBS's experts reckoned an "attractive entry point" had emerged and lifted their recommendation to "buy" with a £25.50 price target. Pub group Marston's was up 3.3 to 148½p after Jefferies analysts turned positive on the company. The same went for Moneysupermarket.com, 4½ higher at 192.9p on an upgrade to "overweight" by JPMorgan Cazenove, and miner Glencore Xstrata, 5.95 better at 314.8p. Analysts at JPMorgan repeated their "overweight" recommendation on the latter company and were upbeat about is ability generate free-cash flow. Finally, profit warnings from hit both lighting technology group Dialight, down 143 at 700p, and Mothercare, which plunged 128½ to 291½p.