LONDON -- Well, it's been another of those weeks for the FTSE 100 (INDEX: ^FTSE). It had hardly broken the 6,100 level before the 6,200 barrier fell, with the index of top U.K. stocks ending the week up 130 points (2%) to 6,284, knocking on the door of 6,300. Of course, while we like to see share prices rising, as Fools we know that those absolute levels are quite meaningless, even if the wider world does seem to attach some kind of emotional importance to them.

Anyway, with the markets being so bullish, this week we have four FTSE 100 risers for you.

United Utilities (UU 0.34%)
United Utilities, a supplier of water and electricity, is one of the week's biggest gains, picking up 34 pence (4.8%) to close Friday at 745 pence. Like the U.K.'s other multiutilities, United is seen as something of a cash cow; in a regulated industry with a captive audience for essential supplies, it is able to pay out most of its earnings as dividends. Current forecasts for the year to March suggest a payout of 4.8%, and investors are prepared to pay good money to get such a strong and reliable income. An interim management statement is due next Wednesday.

Vodafone (VOD 1.19%)
Mobile telecom giant Vodafone gained 8.4 pence (5.2%) to 170 pence. Vodafone stock has been falling in price since last summer, though since the new year it has started to climb back a little. This week's driver seems to have been rumors that the company may be selling off its stake in Verizon Wireless, though as it's such a nice earner for Vodafone, I'm not sure I'd join in the joy. But Vodafone stock does look cheap, on a P/E of 11 for March 2013, and with a 6.5% dividend expected. Some may think that payout will be cut, but Vodafone has plenty of cash that it seems keen to return to shareholders.

Unilever (ULVR 0.78%)
Consumer-brand owner Unilever saw its price jump by 105 pence (4.3%) to 2,533 pence, in the week the company released its latest full-year figures. Turnover in 2012 rose by 10.5% to 51.3 billion euros, though some of that was due to currency exchange gains. But allowing for that, underlying sales still grew by 6.9%. Core earnings per share rose by 11% to 1.57 euros. Unilever is on a relatively high P/E of over 18, but if this kind of growth can continue over the long term, that might be a fair price.

Xstrata (LSE: XTA)
The hard-pressed mining sector has seen mixed fortunes of late, with some of its constituents experiencing a strong recovery. One of those is Xstrata, whose price rose by 46 pence (4%) to 1,183 pence this week, taking the stock up 50% since last summer's low point of 785 pence. In this case it's mainly down to the merger with Glencore, which is pretty much a done deal, but it's looking like the whole sector could be undervalued right now.

What now?
As usual, this week's FTSE trading provided some large share-price movements -- and perhaps some buying opportunities. Indeed, legendary investor Warren Buffett has spent more than $1 billion buying the shares of one of the U.K.'s most successful FTSE large caps.

Clearly he thinks there are bargains to be had within Britain's stock market, and you can discover the details of his investment -- including the price he paid -- by reading this special report. The report -- "The One U.K. Share Warren Buffett Loves" -- is free and can be accessed immediately.

The Motley Fool is helping Britain invest. Better. And with the economy so uncertain, we're urging everyone to read "10 Steps to Making a Million in the Market" -- it may transform your wealth. Click here now to request your free, no-obligation copy.

Further Motley Fool investment opportunities: