Basically, the market's dollar denominated value is going up, but dollars are becoming less valuable. This combines to mean that market value has actually down this year, not up.
Perhaps op can correct me on anything I got wrong.
[1] http://www.marketwatch.com/investing/index/spx [2] http://www.marketwatch.com/investing/index/dxy
Of course, the falling dollar price benefits US exports in the future, so it could be a good time to invest in US, now that it has been performing less stellar compared to the rest of the world.
That I blew most of last month's pay on European indices suggests I think the Maybot and chums are not done wrecking the UK yet :)
I keep hearing that, over and over, for years and years. Eventually it'll be true.
'In the clearest indication yet that there could be a rate rise as early as November, Mark Carney suggested that it was time for the bank to "ease its foot off the accelerator".'
http://www.telegraph.co.uk/business/2017/09/14/bank-england-...
The US economy seems to be less dependent on exports as other countries, and the fortunes of US (tech) companies seem to hinge on other things than exchange rates.
Inflation means the purchasing power of the unit of currency is reduced. iirc it was Keynes who noted that government financing can utilise the margin between real and nominal values, with the benefit of also maintaining animal spirits (bullishness/confidence) as the public sees only price. For economist perspectives: Paul Krugman's blog elaborates on this in a readable way. Mises.org provides one critique. David Harvey another. Dan Amerman provides an CFA/investor perspective (http://danielamerman.com/va/Dow36.html)
The graph linked to above could be viewed as a decline in real value of equities - or the value preserving market response to inflationary pressures (with some degree of non-market support)
The combination of inflation and tax rates is important to understanding the interplay between government, markets and the wider economy. Which is the dog and which the tail is a moot point. Not endorsing, and not by any means the last word, but David Graeber provides an alternative starting point before exploring further: https://www.theguardian.com/commentisfree/video/2015/oct/28/...
When OP talks about dollar adjusted returns of S&P, an analogous mechanism is at work.