HTB/ETB

HTB and ETB describe how easy it is to borrow shares of a particular stock so you can sell it short. Short selling means selling shares you don't own, which requires your broker to first borrow them from someone else (another client, another firm, or an institution) so the sale can actually settle. Whether that borrow is easy or hard determines whether you can short a stock at all, and what it costs.

ETB, or easy to borrow, means the stock has plenty of shares available in the lending market. Brokers keep a running list of these, and normally your platform will let you short them instantly without any extra fees or special approval, because there's ample supply of shares from institutions, other brokers, or the broker's own inventory willing to lend them out.

HTB, or hard to borrow, means shares are scarce, usually because a lot of other traders already want to short the same stock, the float (the number of shares actually available to trade) is small, or the stock is heavily owned by holders who aren't lending it out. When a stock is HTB, your broker may charge a borrow fee (sometimes substantial, quoted as an annualized percentage of the position's value) on top of your regular costs, may only let you locate and short a limited number of shares, or may not let you short it at all that day.

The nuance that trips people up is that HTB status is not fixed and not the same across brokers. A stock can flip from ETB to HTB within hours if short interest spikes, and the fee and availability you see depend on your specific broker's locate inventory, not some universal market number. Also, being hard to borrow is separate from being halted or restricted for other reasons; a stock can be perfectly tradeable to buy while being nearly impossible, or expensive, to short.