Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

Today, a number of companies announced quarterly earnings, but one industry in particular had a number of its key players release results -- the after-market automotive parts and tools industry. Let's take a look at who they were and what they reported.

One of the larger players by market capitalization within the industry is O'Reilly Automotive (NASDAQ:ORLY), with a market capitalization of $15.75 billion after today's stock price increase of 9.04%. That move higher came after the company reported a 23% increase in fourth-quarter diluted earnings per share, which hit $1.40 after sales rose 9% to hit $1.62 billion when compared to the same quarter a year ago. Furthermore, this increase to diluted earnings per share marked the 20th consecutive quarterly increase of 15% or more. The company also reported that year-end sales rose 8%, to $6.65 billion, and a 27% increase to diluted earnings per share, which came in at $6.03.

In addition to the strong quarterly and year-end results, management announced that the board of directors had increased the authorized share repurchase program amount by an additional $500 million, which raises the current program's aggregate authorization to $4 billion. But after the company spent $993 million during 2013 on share buybacks, and more than $3.35 billion since the program was started in January of 2011, the program is left with roughly $645 million to spend on future share buybacks. O'Reilly's management also believes it will produce same-store sales increases of 3%-5% during the coming year and maintain gross profit margins above 50.9%.

Competitor Advanced Auto Parts (NYSE:AAP) also announced earnings this morning, which resulted in shares of the company increasing by 12.74% today. Revenue at Advanced rose 6% year over year to hit $1.41 billion, but that was below the $1.43 billion analysts were expecting. Despite that miss, earnings per share came in at $0.94, which was $0.13 higher than Wall Street had predicted. The company maintained a strong gross margin at 49.8%, but that fell from 49.9% during the same quarter last year, which was explained as a side effect from a higher mix of commercial sales, an area that has lower margins. Lastly, management forecasted that 2014 fiscal year earnings per share will fall within a range from $7.20-$7.40, while analysts had that number pinned at just $7.03 per share. 

The two retailers' promising numbers helped push shares of fellow industry player AutoZone (NYSE:AZO) higher by 6.12% today, despite any major news pertaining directly to the company itself. The move shouldn't concern investors, as the industry is certainly doing well, and it's one in which a number of players can operate without hurting each other. This can be seen by the high profit margins that both O'Reilly and Advanced Auto displayed during the quarter and believe they can maintain.

Furthermore, as Americans continue to keep their vehicles longer, these stores and their products are not only more important, but will likely continue to experience increased sales figures.

Another player that operates heavily within this industry, but in a slightly different fashion, announced earnings today. Shares of tool company Snap-On (NYSE:SNA) rose 7.76% today after beating estimates on both the top and bottom lines. Revenue came in at $797.5 million for the quarter, a 5.9% increase from last year and higher than the $779.5 million analysts were looking for. Earnings per share hit $1.60, again higher than the $1.56 that was expected. One of the areas that management would like to focus on moving forward is expanding its vehicle repair garage, which again would make sense given the average age of vehicles on the road today.