It’s not a good idea to let your politics influence your investments, but a new study suggests some investors do just that. The study, Does Partisanship Shape Investor Beliefs? Evidence from the Covid-19 Pandemic, identified partisan Republicans on the investor social platform StockTwits by searching for terms such as “MAGA”, “stupid Dems”, and “liberal media”.

Although other users became much more pessimistic about stocks during the coronavirus pandemic in March, partisan Republicans were "relatively unfazed". Republicans were more optimistic about stocks that suffered during the bear market, with one exception – they became more pessimistic about Chinese firms such as Baidu and Alibaba.

Note that they didn't become more pessimistic about these stocks during January's Covid outbreak in China; rather, they became pessimistic in mid-March, when new cases in China had fallen but the US crisis was deepening. With Donald Trump and other Republicans often referring to the "Chinese virus" or the "Wuhan virus", it all "points to a political, rather than economic, model for their beliefs". The study notes that the politicisation of stock markets has increased, pointing to Trump's incessant tweeting about the stock market. Partisans "predictably disagree" about issues like environmental policy and abortion, but the fact this divide is also reflected in investor beliefs "perhaps reflects the unprecedented heights of political polarisation we have reached".