Taiwan's top two contract semiconductor manufacturers have reported mixed results for January.

Taiwan Semiconductor Manufacturing Co. (TSMC), the world's largest contract chip-maker, yesterday posted combined revenue of NT$34.569 billion (S$1.5 billion) last month, a 10.6-per cent increase from December.

On a year-on-year basis, the figure was a decline of 2.3 per cent.

The monthly sales increase came after a decline for two consecutive months in November and December. In December sales totaled NT$31.242 billion, the lowest in 22 months.

As for January, sales increased due to rising orders in the period.

The company had forecasted that sales would fall between NT$103 billion and NT$105 billion during the first quarter, about the same as the fourth quarter of 2011.

Based on that prediction, TSMC's February and March sales should each average between NT$34.2 billion and NT$35.2 billion.

The 10.6-per cent increase was in contrast with the 0.67 per cent monthly decline posted by United Microelectronics Corp. Thursday.

On that day, the world's No. 2 made-to-order chip-maker reported sales of NT$8.05 billion for January, a 32-month low. On a year-on-year basis it was a decline of 15.48 per cent.

UMC predicts that sales would drop to their bottom in January and climb back up afterwards.

Analysts forecast that UMC's Q1 sales may decline 5 per cent quarter-on-quarter to NT$23.267 billion, due to an expected reduction in the average sale price of wafers, in US dollar, of the same margin in the January-March period.

In other words, UMC should be making about NT$7.6 billion in sales for February and March each.

TSMC and UMC yesterday closed at NT$76.9 and NT$15, down 1.41 per cent and 0.66 per cent, respectively.