Good, the Bad, and the Ugly of the Jagged U.S. EconomyGet ready for a stock market shakedown. It’s coming. It’s overdue.

I’m not as worried about blue chips. It’s the smaller companies that are all over the place, both operationally and on the stock market.

The lack of uniformity in smaller company sales and earnings exemplifies the jagged state of the U.S. economy. There is no rising tide to lift all boats, that’s for sure. But here are three companies that highlight the good, the bad, and the ugly in this jagged economy.

The Good:

AAON, Inc. (NASDAQ/AAON) has doubled on the stock market since 2010.

Based in Tulsa, Oklahoma, the company manufacturers heating, ventilation and air conditioning (HVAC) units for rooftops. The company sells to new construction and replacement markets, and is about as old economy as you can get.

Its sales in the fourth quarter of 2012 grew a solid 23% to a record $78.0 million, up from $63.4 million in the comparable quarter. Earnings improved significantly, growing 770% to a record $7.6 million.

This position just hit a new record high on the stock market. Management expects another solid year in 2013.

The Bad:

U.S. Auto Parts Network, Inc. (NASDAQ/PRTS) is an online auto parts provider selling aftermarket engine and performance parts, along with accessories.

Sales in its latest quarter (ended December 29, 2012) fell to $62.8 million, down 19% from the comparable quarter. Changing search engine algorithms were an issue.

Earnings were a huge net loss of $30.8 million, or $0.99 per share, compared to a net loss of $7.0 million, or $0.23 per share.

On the stock market, this company is now worth one-quarter of what it was worth last August.

Management said that it expects the downward trend in its revenues and earnings to continue throughout 2013.

The Ugly:

STEC, Inc. (NASDAQ/STEC) makes solid-state drives (SSDs) for data storage in large-scale enterprise environments. The company is headquartered in Santa Ana, California.

Sales in its most recent quarter were $35.1 million, representing a significant drop of 40% from $58.1 million in the comparable quarter and 17% from the preceding quarter.

Earnings were nowhere in sight, as the company generated a huge net loss of $23.2 million, compared to a previous net loss of $3.6 million in the fourth quarter of 2011.

The company missed Wall Street earnings estimates significantly and there is shareholder dissidence. On the stock market, this position has been cut in half since last September.

Overall, large-cap companies definitely have the advantage in a slow-growth economy, but it’s smaller businesses that provide job growth, and this continues to be a real problem.

Near-term action continues to favor large-cap companies, but the risk of correction is going up. Corporate earnings are satisfactory, but this stock market is overdue for a break.