By: Jack Marshall –  The Wall Street Journal

Companies are increasingly trying to “join the conversation” with consumers on social media services including Facebook and Twitter, but they’d rather their competitors didn’t join the conversation too.

In an attempt to protect their intellectual property on social media sites and across the wider Internet, companies are increasingly filing trademark applications for hashtags related to their products and brands.

According to research by Thomson Reuters CompuMark, 1,398 applications to trademark specific hashtags were filed globally during 2015. That number has been growing consistently since 2010, when just 7 companies applied to trademark hashtags.

The number of successful applications also appears to be rising. A total of 103 hashtag trademarks were registered in 2014, Thomson Reuters CompuMark said.

As of 2015, the U.S. leads all countries with the most hashtag applications with 1,042, followed by Brazil with 321, France with 159 and the United Kingdom and Italy with 115.

Hashtags, which originated on Twitter, are typically words or phrases preceded by a hash or pound sign, and are now commonly used across the Internet to signal that posts or messages are related to specific issues or topics.

They’re increasingly being used by marketers as well, often to try to link posts to news or cultural events, or simply in attempts to get people tweeting about specific products, promotions or campaigns.

The problem for marketers, however, is that hashtags can be used by anyone, including by competing companies. A hashtag trademark could help offer some protection.

“You often see companies register their tag lines or slogans so they can protect those trademarks and prevent competitors from using them. A hashtag trademark is the same basic concept,” said Aaron P. Rubin, a partner at law firm Morrison & Foerster LLP.

As a result, major U.S. companies have opted to trademark hashtags in recent years, according to Thomson Reuters CompuMark’s research.

In 2013, for example, Reckitt Benckiser registered the #blamemucus hashtag with the United States Patent and Trademark Office, and used it to spread the word online about its Mucinex brand of cold and flu medicines. The company’s Twitter account frequently prompted people to use the hashtag when posting about and discussing their colds on the social network.

More recent examples include the #sayitwithpepsi hashtag, which was registered in Europe by PepsiCo last year, and #everydaymadewell, which was registered in the U.S. by clothing retailer Madewell.