Press reports have been pretty consistent over the past year or so about the underwhelming financial performance of Twitter.  Here’s the trend line for Twitter shares of stock since the beginning of 2014:

… And beyond the financial performance, I’ve been writing about Twitter’s fundamental business challenges off and on for well over five years now.

While Twitter undoubtedly has its place in the social realm — its place in “breaking news” is a biggie — it remains a frustrating platform for advertisers, which is one reason Twitter’s business model has turned out to be less effective than Facebook’s.

Recent stats from eMarketer reveal that over 50 million Internet users in the United States are accessing their Twitter accounts via any device at least monthly.

That equates to about fifth of U.S. Internet users — and nearly three in ten people active on social networks.

So … this means that many people are seeing ads on Twitter. And that’s confirmed through an evaluation conducted by Cowen & Company which finds that well over half of U.S. adult Twitter users are e encountering ads on their Twitter feed at least every 10 or 20 tweets.

Predictably, most of the advertising pertains to retail, app installations and travel. Those are pretty relevant as broad advertising categories.

It’s just … many Twitter users aren’t finding the ads effective.  Here’s what Cowen’s findings show in terms of user feelings about Twitter advertising:

• Ads on Twitter are relevant and/or insightful: ~3%
• Ads are OK: ~26%
• Ads are not really relevant: ~45%
• Ads are usually a poor fit: ~14%

These results suggest that advertisers need to improve their targeting capabilities significantly if they wish to reach the right audience segments with relevant messages.

More fundamentally, current attitudes about Twitter advertising pose continuing challenges for Twitter as it attempts to further-monetize its platform. The tepid performance of Twitter shares since the beginning of 2014 underscores how the company continues to cast about for answers to that fundamental challenge.  I wonder when (or if) the company will ever figure it all out.