Lost among the earnings reports of big banks Wells Fargo and Citigroup today were analyst-beating results from online brokerage TD AMERITRADE (Nasdaq: AMTD). Beating analysts' earnings expectations by a penny, however, did not curry the stock any favorites this morning, as it was down as much as 2.5% in today's trading.

What spooked them?
Investors appear to be concerned about the company's declining revenues, which fell 1% short of the same quarter last year. This is partly because many "clients continue to hesitate in their trading and investing in the face of all the uncertainty in the markets right now," according to AMERITRADE President and CEO Fred Tomczyk. This has resulted in lower average brokerage fees per transaction.

After averaging nearly 416,000 trades per day during the third quarter, worries about the debt crisis in Europe pushed average trade volume to just over 367,000 per day during the fourth quarter. Though the fourth quarter tends to be light on trading in general, this number represented a drop of nearly 4,500 trades a day from the same period in 2010. If AMERITRADE customers regain confidence in the markets, it surely bodes well for the company going forward.

How will others compare?
With competitors Charles Schwab (Nasdaq: SCHW) and E*TRADE Financial (Nasdaq: ETFC) reporting earnings within the week, it will be interesting to see if this trend is something shared by all online brokers or if it something exclusive to AMERITRADE.

Schwab analysts are expecting $0.13 a share in earnings, while those that follow E*TRADE are anticipating $0.20 A share. Positive earnings on E*TRADE's part will be better than its fourth quarter last year, which saw a loss on $0.11 per share. E*TRADE struggled a bit during 2011, but it has made some changes for 2012 that should help it improve on last year's performance.

What it means to you
While these companies only represent a small piece of the economy, their results can help indicate the general fervor of investors in regards to the stock market. When they report high volumes, it means that investors have some confidence in the market. When their numbers sag, it means that people are hoarding money waiting for some semblance of normalcy to return to their investing world. Add these companies to your My Watchlist to keep an eye on these microcosms of the market.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.