shensor 发布了更新 1年， 11个月 之前
There’s been a lot of talk about the “Trump Rally,” and just how historic it’s been. MarketWatch called it “the best 50-day performance for a GOP commander-in-chief ever[.]” The media loves to overstate things, and it made me want to dig in and figure out what is actually going on.
Before we dive in, I want to make clear that I have no clue what the Trump presidency will mean for the market or the economy at large. No one knows. The US economy is huge and multifaceted, and the president has a lot less control over what happens than most people think.
It’s nearly impossible for the president to single-handedly grow (or shrink) the economy. The market is going to do what it’s going to do. But we can control how we react to what the economy and the market do and what the press says or predicts about market behavior.
The financial press makes its money through advertising, and advertising dollars roll in when you have a lot of readers. They get readers by hooking us on the fear vs. greed cycle, making you think that this time it’s different.
I’m sure they prefer the market to go up (the reporters have 401(k)s too), but they’ll make the most of whatever is happening in the markets – especially when they can tie it into something as polarizing as the new president.
So let’s cut through the noise of the politicians, analysts, and media and look at the data.
A Look at the Trump Rally Numbers
What we want to know is whether or not the US equity market has looked substantively different from other periods in time since Trump’s election and inauguration. The numbers can be cut up all sorts of different ways, but let’s keep it straightforward.
Using the S&P 500 index as our proxy for the US stock market, we’ll look at two time periods: the last two months (January and February 2017 – the period Trump has been in office), and the previous four months (November 2016 – February 2017 – the period since Trump’s election) and compare them to historical two- and four-month periods. Here are the Trump Rally numbers.
Previous Two Months (January – February 2017) 5.94%
Previous Four Months (November 2016 – February 2017) 12.04%
Data courtesy of Dimensional Fund Advisors.
I like to start with as much data as possible to get a good base line. So, let’s start by comparing against the total history of the S&P 500 Index since January 1926.
We’ll use monthly rolling returns to see how many periods did better or worse than the Trump Rally. The question here is: If you were to pick a random two- or four-month time period, how likely is it that it would be better than what we have seen recently?
2-Month Rolling Periods 4-Month Rolling Periods
Total Number of Rolling Periods 1,093 1,091
Number of Observations Better than Trump Rally 291 208
Percent Better than Trump Rally 27% 19%
Average Total Return
Standard Deviation of Total Returns 11.41% 8.15%
Data from 1/26 – 2/17. Data courtesy of Dimensional Fund Advisors.
So we can see that the most recent two- and four-month periods have been reasonably good. They are both a good deal above their respective average returns (though solidly within one standard deviation of the average return). But they were hardly unprecedented.
If you select any random month from the period, you have more than a 1 in 4 chance that the subsequent two months would beat the two months we’ve just had, and almost a 1 in 5 chance that the subsequent four months would have beaten our last four months.
In other words, compared to the long-term data, the Trump Rally has been pretty good, but nothing much to write home about.
But what if we focus a little bit more tightly. Since this is as much a political story as a financial one, what if we look at what the market’s did from 2008-2016 during the Obama administration?