Prothena (PRTA) Short Interest Ratio & Short Volume

Short interest is the volume of Prothena shares that have been sold short but have not yet been covered or closed out. As of April 15th, traders have sold 7,920,000 shares of PRTA short. 18.64% of Prothena's shares are currently sold short. Learn More on Prothena's current short interest.

The short interest ratio, also known as the "days to cover ratio", is calculated by dividing the number of shares of a stock sold short divided by its average trading volume. A short interest ratio ranging between 1 and 4 generally indicates strong positive sentiment about a stock and a lack of short sellers. A short interest ratio of 10 or greater indicates strong pessimism about a stock. PRTA shares currently have a short interest ratio of 17.0. Learn More on Prothena's short interest ratio.

As of the most recent reporting period, the following institutional investors, funds, and major shareholders have reported short positions of Prothena: Wolverine Trading LLC, Group One Trading LLC, Citadel Advisors LLC, Boothbay Fund Management LLC, Susquehanna International Group LLP, Concourse Financial Group Securities Inc., and Walleye Capital LLC. These positions are disclosed in Form 13F filings with the Securities and Exchange Commission.

Companies that have a short interest as a percentage of float below 10% indicates positive investor sentiment and few short sellers. Stocks with a short interest percentage above 10% is considered high, suggesting some investors are pessimistic about the stock. Companies with a short interest percentage of 20% or more indicates widespread negative sentiment. 18.64% of Prothena's floating shares are currently sold short.

Prothena saw a decline in short interest in the month of April. As of April 15th, there was short interest totaling 7,920,000 shares, a decline of 5.5% from the previous total of 8,380,000 shares. Changes in short volume can be used to identify positive and negative investor sentiment. Investors that short sell a stock are betting that its price will decline in the future. An increase in short sale volume suggests bearish (negative) sentiment among investors. A decrease on short sale volume suggests bullish (positive) sentiment.

Prothena currently has issued a total of 53,827,000 shares. Some of Prothena's outstanding shares are available for trading, while others are subject to various restrictions. The public float, also referred to as floating shares or "the float", are shares that publicly owned, unrestricted and available to trade on the open market. Prothena currently has a public float of 42,500,000 shares.

18.64% of Prothena's shares are currently sold short. Here is how the short interest of companies in the industry of "pharmaceutical products" compare to Prothena: Mirum Pharmaceuticals, Inc. (16.96%), Bausch Health Companies Inc. (3.09%), Beam Therapeutics Inc. (23.74%), NewAmsterdam Pharma (8.30%), Vericel Co. (9.60%), Belite Bio, Inc (0.22%), Tarsus Pharmaceuticals, Inc. (23.89%), Janux Therapeutics, Inc. (18.91%), Schrödinger, Inc. (15.93%), Arrowhead Pharmaceuticals, Inc. (10.38%),

As of the most recent reporting period, the following stocks had the largest short interest positions: Invesco QQQ ($21.71 billion), iShares 20+ Year Treasury Bond ETF ($9.48 billion), Strategy Incorporated ($8.92 billion), Charter Communications, Inc. ($3.86 billion), Apollo Global Management, Inc. ($3.86 billion), Capital One Financial Co. ($3.72 billion), Super Micro Computer, Inc. ($3.47 billion), AppLovin Co. ($2.64 billion), VanEck Semiconductor ETF ($2.46 billion), and The Kroger Co. ($2.33 billion). View all of the most shorted stocks.

Short selling PRTA is an investing strategy that aims to generate trading profit from Prothena as its price is falling. PRTA shares are trading down $0.50 today. To short a stock, an investor borrows shares, sells them and buys the shares back on the public market later to return it to the lender. Short sellers are betting that a stock will decline in price. If the stock does drop after selling, the short seller buys it back at a lower price and returns it to the lender. The difference between the sell price and the buy price is the trader's profit.

A short squeeze for Prothena occurs when it has a large amount of short interest and its stock increases in price. This forces short sellers to cover their short interest positions by buying actual shares of PRTA, which in turn drives the price of the stock up even further.

Short interest is typically published by a stock exchange once per month. However, NASDAQ publishes a report for U.S. stocks, including PRTA, twice per month. The most recent reporting period available is April, 15 2025.