Source: Sharecast
The FTSE 100 was called to open up around 30 points.
Stephen Innes, managing partner at SPI Asset Management, said: "Wall Street did what it does best - shrugged off a ratings downgrade with the kind of casual arrogance only a $35 trillion debtor can muster.
"After Moody’s notched US sovereign credit down late Friday, equity markets opened this week with a brief panic… but not a panic anyone really bought into.
"The S&P 500 clawed back a full 1.1% intraday drop and came within a hair of breaking into bull market territory - before stalling out just shy of euphoria as retail earnings nerves set in."
In corporate news, bakery chain Greggs held annual guidance after reporting a 2.9% rise in like-for-like sales in the first 20 weeks of the year, with an improved performance in the last 11 weeks supported by better trading conditions.
Total sales in the period to 17 May were up 7.4% at £784m. Greggs also left its cost inflation outlook unchanged.
Investors will also be mulling results from Vodafone, SSP, Cranswick and Hilton Food, among others.