Or you could tax capital gains at the same rate as income. Poor people generally don't have capital to have gains on.
For one, capital gains are voluntary, and sellers more or less choose when to accrue them (and time them against losses in portfolio to minimize the impact).
For two, bulk of the money in the market is paying capital gains tax of 0%, as it belongs to a retirement account, charitable foundation, pension fund, foreign entity, university endowment, trust fund or some other tax-exempt structure. US-affiliated taxable accounts are not the majority in the market (source on this is Ken Fisher's Debunkery http://www.ken-fisher-debunkery.com/ published in 2011, I'm not sure whether situation changed since then).
That, or perhaps, instituting a 3% transaction tax for every damn unit of debt or equity sold. Whether its a broker or bot, tax it.
But, of course, most of the ruling class wants to talk about "skin in the game" and advocating regressive sales or property tax.
That is also not entirely true. Sales of publicly traded stock by large shareholders is public information, and as an example, Mark Zuckerberg, sold a $2.3 billion chunk of shares in 2012 post-IPO when he became eligible http://www.theguardian.com/technology/2013/dec/19/facebook-m... and has not sold a single share ever since https://finance.yahoo.com/q/it?s=fb except for a disposition (charitable contribution). He probably doesn't need to either, there's a long wait before that bank account gets depleted.
It does not make sense for 1% to be transacting heavily in the assets they own, and if they're company officers they're frequently sending negative signals by doing that.