Blue chip shares gave up some of yesterday's stellar gains in afternoon trading, as traders weighed fears over central banks tightening their stimulus measures.
London market's main benchmark climbed towards its record high in the previous session as sterling's value was hit by market fears of a hard Brexit.
But today (5 October) the FTSE 100 Index fell 22.2 points to 7,052.2, despite the pound falling further in early trade – hitting $1.2687 – before recovering slightly. Sterling also fell to a five-year low against the euro, hitting €1.1308 at one point.
The FTSE 250 Index fell 148.5 points to 18,193.6.
Traders were worried by reports that the US Federal Reserve will hike interest rates in December as its tentative economic recovery continues and the European Central Bank (ECB) will also tighten monetary policy by cutting back on its €80bn (£70bn, $90bn) of monthly bond purchases. Cheap cash favours investors.
IG market analyst Joshua Mahony said: "The bullish sentiment that drove yesterday's sensational rise in the FTSE has been dampened today, with markets largely responding to the fears that perhaps the seemingly unlimited ECB quantitative easing could be limited after all."
Tesco was the biggest gainer in the top flight after it said half-year profits dropped by more than a quarter, but it still managed to rack up a third quarter in a row of sales growth as its turnaround gains traction.
The UK's biggest supermarket posted a 28.3% fall in bottom-line pre-tax profits to £71m for the six months to August 26 after being hit by the sector's fierce price war.
But it added like-for-like sales, a key measure of growth in the industry, surged by 0.9% in the second quarter. Shares jumped 25.2p to 214p.
In afternoon trading the biggest risers in the FTSE 100 Index were Tesco (+25.2p to 214p), Anglo American (+27.7p to 1,014p), Morrisons (+5.5p to 226.1p), Marks & Spencer (+6.4p to 335.3p) and Standard Chartered (+9.8p to 659.4p).
The biggest fallers in the FTSE 100 Index were United Utilities (-30.5p to 964p), Polymetal International (-27p to 901p), Intu Properties (-8.3p to 292.5p), Travis Perkins (-43p to 1,565p) and Land Securities (-25p to 1029p).
In afternoon trading the biggest risers in the FTSE 250 Index were Centamin (+4p to 149.1p), Aldermore Group (+4.3p to 180.4p), Vedanta Resources (+12.5p to 618p), Brewin Dolphin (+5.1p to 274.7p) and Kaz Minerals (+3.8p to 235.7p).
The biggest fallers in the FTSE 250 Index were Hastings Group (-10p to 218.5p), Allied Minds (-14.7p to 337p), IP Group (-7p to 164p), Hochschild Mining (-11p to 266p) and Countrywide (-8.4p to 216p).