In these and other specific cases, the big share moves are easy enough to justify. The political risk associated with investing in certain companies is concretely lower. But for the market in general the City's celebratory mood seems misplaced.
The most plausible way of interpreting the election result is as a vote for continuity. People are happy enough with the way the economy performed under the previous Tory-led administration that they didn't want to risk a new approach. Whether Chancellor George Osborne's austerity-driven plan was instrumental or not in producing the economic recovery is a moot point. As ever in economics, there is no counterfactual: we do not know, and never will, whether government borrowing would now be lower as a share of GDP had Shadow Chancellor Ed Balls been in charge with a fiscally looser approach.
But in one crucial policy area there is no continuity: Europe. With the Liberal Democrats as coalition partners, the previous government could pay little more than lip service to eurosceptic Conservative backbenchers. With a parliamentary majority of just 12, the new government is completely dependent on them. And that puts Mr Cameron on a collision course with the City.
Before the end of 2017, we will all go to the polls again to decide whether we want Britain to be part of the European Union. The Confederation of British Industry (CBI) wants the country to stay within a reformed EU. This sounds similar to what Mr Cameron has argued for - and on most points it is. In common with the Tory leadership, the CBI likes the single market but doesn't like European regulations, particularly around working hours and conditions. But on the crucial doorstep issue of immigration the interests of businessmen and politicians are fundamentally misaligned.
The CBI supports the free movement of labour, which was inscribed in the 1957 Treaty of Rome as a founding principle of the European Economic Community (renamed the EU in 1993) and allows Eastern Europeans, most topically, to work in Britain without a visa. "Most businesses want Polish and Eastern European engineers to keep their machines working," John Cridland, the CBI's director general, told the BBC's Today Programme after the election.
Meanwhile, many Tory backbenchers are unhappy with free movement of labour because it leads to 'uncontrolled immigration'. This partly reflects the broadening appeal of the UK Independence Party, which won just one seat in the general election but with as many votes as the Liberal Democrats and Scottish National Party combined. Little wonder the 2015 Conservative election manifesto stressed the need to "control immigration" and reiterated a pledge to bring annual net inflows below 100,000.
This pledge was frustrated in the last parliament by the legal impossibility of blocking workers from within the EU. One unintended consequence was a reduction in student numbers from outside the EU, harming higher education, a key British export, as well as graduate recruitment - another CBI gripe. Unless Britain leaves the bloc, this pattern is only likely to be repeated in the current parliament.
The Tory high command seems to be hoping for a deal on benefits. Agreement with other EU leaders on the need to clamp down on 'benefit tourism' - citizens of one state using public services in another - is not unrealistic, and would please backbenchers without alienating business. The problem is that there is little evidence much benefit tourism actually exists, so clamping down won't curb immigration. The numbers can only be controlled if Britain quits the EU.
That would be risky for British business, because it is unclear what institutional arrangements would replace the bloc. With free trade, exporters might thrive - as they have thrived outside the euro - but if the negotiators misstep and tariffs spring up, it would do much damage to the country's open trading economy. There is much for the UK stock market to worry about as the Tory government tries to placate backbenchers, business and Brussels alike over the next two years. Don't expect the post-election relief rally to last.
