CREDIT SUISSE: Here's how high-frequency trading has changed the stock market

The rise of high-frequency trading in the US stock market has been nothing if not controversial.

The practice, which uses complex algorithms to analyze multiple markets and execute orders based on market conditions, has divided Wall Streeters into two camps: those who think the stock market has benefited from their existence, and those who argue to the contrary.

What's not in doubt, however, is their overall impact on the stock market.

"They've firmly established their place in the market ecosystem, primarily serving as a facilitator connecting buyers and sellers through time, but also frequently criticized in that role for being superfluous, or worse, predatory," Credit Suisse strategist Ana Avramovic said in a recent note.

"Whatever your view, their impact has been wide and, likely, lasting," she added.

In a note, titled We're All High Frequency Traders Now, Avramovic ran through four ways HFTs have impacted the market.