Silicon Motion Tech (SIMO) and Key Energy Services (KEG)

The top-performing Zacks #1 Rank on Monday is a company that's well known to readers of this article: Silicon Motion Technology Corporation (SIMO - Snapshot Report).

This fabless semiconductor company was highlighted in this space on Sep 13 and Aug 9. This time, though, it really showed off by gaining nearly 12.5%, making it the only Zacks #1 Rank in double digits.

Volume more than doubled to 1.07 million from the daily average of 506,000.

As you probably all ready know, it's easier for a company like SIMO to hold a Zacks #1 Rank, since there are only 3 total estimates for this year and next each. Regardless of its representation though, it still needs to perform.

In its second-quarter report from late July, Silicon Motion Technology actually missed the Zacks Consensus Estimate by a penny, but it more than made up for it by raising its full year guidance. In fact, the company believes it is on track to deliver the largest annual revenue in its history.

Earnings estimates for 2011 and 2012 have stood still over the past month, but retain the upward momentum earned from its positive outlook. The Zacks Consensus Estimate for this year has advanced 17.5% in 60 days to 74 cents per share from 63 cents.

Meanwhile, the Zacks Consensus Estimate for 2012 is 90 cents per share, which has gained 7.1% in 2 months and suggests year-over-year profit growth of more than 21%.

SIMO is scheduled to report its third-quarter results on Halloween. The Zacks Consensus Estimate for the quarter is at 17 cents.

There were a few energy-related companies that made it pretty high on the Zacks #1 Rank Top Performers List on Monday, led by Key Energy Services, Inc. (KEG - Snapshot Report).

This provider of onshore oil and gas well services gained a little more than 9% today, while volume soared to 4.8 million from the daily average of 2.4 million.

In its second-quarter report, earnings per share of 23 cents topped the Zacks Consensus Estimate by 15%. Earnings estimates moved solidly higher following the report.

There's been some minor movement in expectations since that announcement, but the best way to judge this company's momentum is still to look 60 days back.

The Zacks Consensus Estimate for this year is currently 99 cents per share, or more than 15% better than 86 cents from 2 months ago. As for 2012, the Zacks Consensus Estimate has climbed 19% to $1.75 per share from $1.47.

Also, analysts currently see year–over-year profit improvement of nearly 77% for 2012 over 2011.

Read the full analyst report on KEG

Read the full analyst report on SIMO