Wall Street woke up today to an announcement from Mr. Trump that he intends to place a tariff on all goods coming into the US from Mexico.  The levy will be in effect until that country prevents immigrants/asylum seekers from reaching its border with the US.  The initial rate will be 5%, escalating to 25% by October.

As an American, I think I can understand the issues the administration wants to address.  But I find it more than a little unsettling that there seems to be no coherent, well-reasoned plan being implemented.  I’m pretty sure tariffs are not the way to go.  Also, both sides of the aisle in Congress appear to be eerily content to watch from the sidelines, rather than make it clear that Mr. Trump does not have authority to levy tariffs without legislative consent (my personal view, for what it’s worth) or limit/revoke that authority if the president does have it now.

As an investor, however, my main concern is the much narrower question of how Washington will affect my portfolio.

As to Mexico:  let’s say the US sells $300 billion yearly to Mexico and buys $350 billion.  Most of that is food and car parts.  Even if we sell less to Mexico because of retaliatory tariffs and if imported goods are 15% more expensive–to pluck a figure out of the air–the total direct negative impact on the US + Mexican economies would probably be a loss of around $100 billion in GDP.  How that would be split between the two isn’t clear, but the aggregate figure is 8% of Mexican GDP and 0.5% of US GDP.  So, potentially much worse for Mexico than for the US.

Given the nature of US-Mexico trade, the negative economic impact in the US will be concentrated on lower-income Americans.  If earnings reports from Walmart and the dollar stores are to be believed (I think they are), these are people whose fortunes have finally, and only recently, begun to turn up post-recession.

From a US stock market point of view, neither autos nor food has large index representation.  My guess is the negative impact will be roughly equally divided between negative pressure on directly-affected stocks, including names that cater to the less affluent, and mild downward pressure on stocks in general from slower domestic growth.  Because small caps are more domestically focused than the S&P 500, only half of whose earnings come from the US, the Russell 2000 will likely suffer more than large caps.

There are deeper, long-term questions that Washington is raising–about whether the US is an attractive place to establish manufacturing businesses and whether it can be relied on as a supplier to buy from.  In addition, it’s hard to figure out what government policy today is–for example, how new tariffs on Mexican imports square with just-reworked NAFTA, or how imposing tariffs that hurt domestic car manufacturers square with the threat of tariffs on imported vehicles, which do the opposite.

Neither of these concerns are likely to have a significant impact on near-term trading.  But heightened Washington dysfunction must even now be becoming a red flag in multinationals’ planning.