Twitter shares witnessed a significant surge in the short interest in November. As of Nov. 28, there was short interest totaling about 30.5 million shares, which is an increase of 12.1% from the Nov. 14 total of about 27.2 million shares. At present, around 6.9% of the company’s shares are sold short.

Twitter Inc Short Interest Rises 12% In November

Analysts ratings, insider selling

Recently a number of analysts assigned ratings to the micro-blogging company. Zacks maintained its Neutral rating on the stock in a research note on Friday and assigned it a price target of $39 per share. Also on Friday, Oppenheimer analysts initiated coverage on Twitter shares and assigned a Market Perform rating on the stock with a price target of $36 per share. Pivotal Research analysts upgraded Twitter to Buy from a Hold rating and assigned it a price target of $42 per share. Twitter presently has a consensus rating of Hold and an average target price of $50.24 per share.

In separate news, Twitter CEO Richard Costolo offloaded 141,730 shares of his holdings in a transaction dated Dec. 15.. Costolo sold the shares at an average price of $37.52 for a total value of about $5.3 million, according to a regulatory filing with the Securities & Exchange Commission.

Also Twitter co-founder EV Williams offloaded more than 719,000 shares, totaling approximately $28.7 million last month. Another insider, Jack Dorsey, is also reported to have sold $2.1 million worth of his shares last month.

Should Twitter investors be worried?

Currently Costolo’s family trust owns zero Twitter shares after selling off more than 500,000 shares in the last two months. According to a Twitter spokesperson, the shares were sold under the pre-arranged stock trading plan filed more than 90 days ago.

“Dick has sold shares under a plan filed in the summer and his total sales represent less than 10% of his total equity in Twitter,” the spokesperson said.

Back in April, the micro-blogging site’s top executives, including Costolo, Williams and Dorsey, stated in an SEC filing that they did not have any “current plans” to offload their shares even after the end of the lock-up period.

According to a report from Business Insider, these recent insider sales are making investors nervous on the stock. The report stated that one of the company’s major institutional investors was not happy with them. Year to date, shares of the micro-blogging company are down by over 40%.