Solid results at heavyweight HSBC boost FTSE 100

* FTSE 100 gains 0.5 percent

* About 50 points from last week's 5-month high

* HSBC rises up 2.5 percent after results prove robust

* Weir, Ryanair warn on profits

By Toni Vorobyova

LONDON, Nov 4 (Reuters) - Britain's FTSE 100 share index pushed ahead on Monday, as gains in its biggest stock HSBC after solid results outweighed losses in the airline and engineering sectors following profit warnings.

HSBC advanced 2.5 percent after profits rose by a tenth in the last quarter, year-on-year, meeting analyst expectations and reassuring investors who have been unnerved by weak numbers from several peers.

Investor (Other OTC: IVSBF - news) interest was further fanned by the stock's underperformance over the past three months, which has left it at its steepest discount to the FTSE 100 since February 2012, and second steepest in the past 5 years based on 12-month earnings expectations, according to Thomson Reuters Datastream.

The bank, which accounts for 7.5 percent of FTSE 100 capitalisation, was responsible for nearly half the index's gains on Monday.

"We have it as one of our preferred selections in the sector ... Their statement was a reflection that things are not that bad out there," said Peter Botham, CIO at Brown Shipley.

"Fundamentally we are still optimistic on the outlook but the biggest uncertainty is whether equities now fully reflect the likely growth of next year, or whether there is still further to go."

Aside from HSBC, the corporate newsflow offered some cause for caution, with profit warnings from engineering firm Weir Group and budget airline Ryanair sending their respective shares down 7.1 and 11.6 percent.

Ryanair results also weighed on rival Easyjet (Other OTC: EJTTF - news) .

The FTSE 100 was up 33.87 points, or 0.5 percent, at 6,768.61 points by 1140 GMT, moving back towards a five-month high of 6,819 hit last week.

Mining (LSE: MIR.L - news) stocks climbed 1.4 percent after activity in China's services sector expanded at the fastest pace in 13 months in October in a further sign that the economy has stabilised.

Growing expectations in the market that the ECB will strike a more dovish tone at its latest meeting also helped the mood, with some expecting an interest rate cut this week following a surprise drop in inflation in October.

"The China data is helping the miners, but over and above that we've got ... perceptions of further easing from the ECB - a lot of people are speculating that they'll cut rates this week," Michael Hewson, chief market analyst at CMC Markets, said. (Additional reporting by Tricia Wright; Editing by Louise Ireland (Other OTC: IRLD - news) )