UK shares are absolutely flying this morning (6 May). As I’m writing this, the FTSE 100 is up 2.2%. What’s going on?

I’ve just checked out my Self-Invested Personal Pension, and it’s fun all the way. Rolls-Royce Holdings, mining stocks, the banks, housebuilders, International Consolidated Airlines Group, even beaten-down spirits giant Diageo are all up between 5% and 9% on the day.

There’s inevitably an exception. Oil giant BP has slipped more than 3%. And it’s plunging for exactly the same reason almost everything else is flying. The Iran conflict.

Have we left it too late to buy cheap shares?

Since the war began on 28 February, markets have been at the mercy of news from the Gulf. When Donald Trump says all is going well, the oil price falls and shares soar. When the missiles start flying, the reverse happens. Yesterday, a barrel of Brent crude hit $112, and the FTSE 100 was plunging. Today, Brent is down to $102, and it’s flying.

This morning’s rally follows US suggestions that the “offensive” stage of the war with Iran is over. Time will tell. We’ve had weeks of this, and there’s likely to be more volatility to come. But it does remind us of an old lesson. Investors shouldn’t panic and sell in a crisis, because they’ll miss great days like this.

What they can do is turn market volatility to their advantage by snapping up their favourite stocks at lower prices on the bad days. I grabbed my chance on Friday (1 May), buying NatWest shares after they dipped 4.5% on poorly received Q1 results. I’m feeling a bit smug today, as they’re up 5.1%. So are there other FTSE 100 bargains out there, despite today’s rally? I think there are.

Are GSK shares a bargain buy?

Recent weeks have bumpy for pharmaceutical giant GSK (LSE: GSK). The shares have nudged up today, but they’re still down 11.4% over the past month. Last week (29 April) GSK published Q1 results showing sales up 5% to £7.6bn and underlying operating profit rising to 10% to £2.7bn.

However, the board disappointed markets by holding both 2026 guidance its 2031 sales outlook for more than £40bn. GSK shares sank on the day. Long-term investors won’t be too unhappy though. The GSK share price is still up 35% in a year, with dividends on top. So is the dip a chance to get in at a lower valuation?

I think it may be. GSK’s trailing price-to-earnings ratio is now a modest 10.8, while its forward dividend yield has crept up to 3.75%. In 2027, it’s forecast to top 4.1%.

There are risks with every stock. GSK needs to keep its pipeline of new treatments flowing. Net debt has crept up to £15.6bn. Governments are keen to squeeze drugs prices, which threaten margins. If GSK fails to beat that ambitious 2031 sales target, the shares could struggle.

Yet I think investors keen for exposure to the healthcare sector consider taking advantage of the recent dip. As GSK shows, there are always bargain buys out there, even on brilliant days like today.