HP plunges 20%; S&P opens lower

US markets have opened lower as investors take a dim view of Hewlett Packard's latest acquisition and send its shares down 20%.

The S&P 500 opened 0.7% lower, falling to 1,134, with the Dow Jones down 0.8% at 10,907 and the Nasdaq falling 0.2% to 2,376, before losses were stemmed shortly after. After losing 6% yesterday, HP was down a further 21% at $23.3 in early trading following the announcement of a strategic overhaul and its $11bn deal to buy FTSE 100 software firm Autonomy. The offer represented a 79% premium to Autonomy's 18 August closing share price. The FTSE continued to hover around the 5,000 mark, trading 1.8% lower at 5,002 in the early afternoon. In Europe, the Dax was down 193 points at 5,409...