US financial markets may be betting that the Trump administration's budget policies will stimulate economic growth and inflation, but they're cheered by this prospect only because of deeper fears that America and the advanced economies have entered an era of persistently weak growth.
America's rate of growth has been slowing for decades, starting long before the onset of the global financial crisis.
As part of this, America's rate of productivity improvement has been weakening, despite a short-lived uptick in the 1990s.
So the hunt's been on for factors that may be causing this slowdown. There are many suspects. But one you often see mentioned by economists such as Professor Paul Krugman is a decline in the strength of competition in many American markets.
If markets are significantly less competitive, you'd expect this to mean consumer prices that are higher than they might be, profits that are higher, less innovation, slower productivity improvement, worsening inequality and slower growth.
But what's the evidence of reduced competitive pressure? Earlier this year President Obama's Council of Economic Advisers issued a paper reviewing the evidence, which I'll summarise.
There are various ways to measure the degree of "concentration" in an industry – that is, how much of the business done by an industry is captured by a small number of large firms.
Figures collected by the US Census Bureau show that, over the 15 years to 2012, the share of total sales revenue earned by the 50 largest firms in 13 broad industry categories fell in three, was unchanged in one but increased in nine.
If 50 sounds like a lot of firms, remember this is America, whose economy is about 12 times bigger than ours.
Sales concentration was highest among utilities – electricity, gas and water – at 69 per cent, which isn't surprising considering many are natural monopolies. Even so, concentration increased by almost 5 percentage points.
After that came finance and insurance, where concentration was up by 10 percentage points to more than 48 per cent, followed by transportation and warehousing (up more than 11 points to 42 per cent) and retail trade (up 11 points to 37 per cent).
This picture is confirmed by studies of specific industries, the briefing paper says. One study of the national market for loans found that, over the 30 years to 2010, the top 10 banks' market share increased by 20 points to 50 per cent.
For deposits, the market share increased from 20 per cent to almost 50 per cent.
Another study found that, for hospital markets over the decade to 2006, a common measure of concentration increased by about 50 per cent, to a degree equivalent to having just three equal-sized competitors in a market.
A different measure of possibly reduced competition comes from looking at what's happened to the rates of profitability of big firms.
When researchers take the rates of return on invested capital for listed US companies, then rank them from highest to lowest, they find that for firms at the 90th percentile (that is, 10 per cent down from the top; 90 per cent up from the bottom) their rate of return is five times higher than for the median (dead middle) firms.
A quarter of a century ago, the 90th percentile firms' rate of return was closer to twice the median firms'.
This suggests some firms are better able to extract "economic rent" than they were. Economic rent is the profit you make that exceeds what you'd need to earn to be willing to remain in the industry.
Yet another indication comes from the "long-term downward trend in business dynamism", as indicated by a steady decline since the late 1970s in the proportion of new firms entering markets each year.
This is while the proportion of firms exiting markets each year has been little changed. Since the entry rate has now fallen to be equal to the exit rate, the total number of firms – which used to grow by about 6 per cent a year – is now unchanging.
Part of the explanation for the decline in the number of new firms could be rising "barriers to entry" into many industries.
This could be caused by increased federal, state or local licensing requirements, ever-rising economies of scale or data-mining information advantages to incumbent firms, or successful lobbying for government rules to protect against new entrants.
Labour market dynamism – how often workers change employers – has also declined since the 1970s.
This could have many causes, including no-poaching agreements between employers and greatly increased occupational licensing, which limits people's freedom to move between states.
The briefing paper notes it's not yet clear how these various indicators suggesting the US may be suffering a fall in competition within its markets fit together.
Turning to possible causes of reduced competition, it notes the problem of "common ownership". Researchers have argued that institutional investors who are large owners of the biggest firms in a particular industry, implicitly encourage those firms not to compete with each other, thus raising the investors' profits.
According to other research, the role of institutional investors has grown over the past 30 years so that, in 2014, they controlled 61 per cent of worldwide investment assets.
One anti-competitive development the briefing paper doesn't mention is the US Congress's willingness to keep extending the lives of existing and future patents and copyright.
Meanwhile, US government trade negotiators use bilateral preferential trade deals – going by the Orwellian name of "free trade agreements" – and plurilateral deals such as the Trans-Pacific Partnership agreement to press partners like us to extend the lives of our patents and copyright to fit with the Yanks' domestic arrangements.
Maybe one reason economic growth is slowing is that the world's multinational corporations are getting too good at finding ways to inhibit competition between them, including by enlisting the help of governments.