Broker tips: Shell, ITV, RSA Insurance, G4S

"Through [recent] outperformance and the more aggressive response to the challenging environment among some peers we see the shares as offering less relative value and hence are cutting the rating," UBS said as it lowered its target price for the shares from 2,400p to 2,130p.

ITV's share price was given a boost on Monday by Westhouse Securities which upgraded its stance on the shares from 'neutral' to 'add' after an "impressive" performance by the broadcaster and producers in 2014.

"We remain bullish on the group’s fundamentals, have materially increased our [earnings] and [dividend] forecasts and expect attractive growth in these metrics with the former also likely to be boosted by acquisitions," said analyst Roddy Davidson, as he raised his target price from 228p to 267p.

Credit Suisse has lowered its target price for RSA Insurance from 525p to 475p after "disappointing" 2014 results from the company last month, though it still maintained an 'outperform' rating on the stock.

"Despite limited near-term excitement, we continue to see medium to longer term risks to the upside. This could be derived from further clean-up of legacy items, a reversal of recent headwinds in terms of FX and bond yields, and potential for M&A."

Shares in security group G4S remain expensive, according to Deutsche Bank, but a lack of clear negative catalysts has prompted the broker to lift its rating from 'sell' to 'hold'.

While Deutsche Bank is still cautious about longer-term potential at the company, top-line growth has surprised on the upside and shown no signs of a slowdown so far. The bank has upgraded its target price for G4S shares from 220p to 280p.