Markets were performing well in early trading on Friday, extending gains made last month, ahead of the all-important jobs report in the US this afternoon.The FTSE 100 rose a total of 6.4% in January alone, the best January performance since 1989.However, as Joe Rundle, head of trading at ETX Capital, explains, strong gains in January are not always a good indicator of how the rest of the year will pan out. "Strength in the first month of the year is not exactly a sufficient signal to go by and investors should adopt a level of caution for the months ahead," he said in an e-mail this morning.Nevertheless, stocks were given support this morning by economic news out of China, where the manufacturing sector continues to expand. While the HSBC manufacturing purchasing managers' index (PMI) beat forecasts, rising from 51.5 to 52.3 in January, the official manufacturing PMI disappointed, falling from 50.6 to 50.4."Now, there's two ways we can look at this," said market analyst James Hughes from Alpari. "Firstly, the two pieces of data conflict, as one suggests the recovery has hit some speed bumps which means the first quarter may not be quite as strong as some had hoped. On the other hand, both numbers are still above 50, which suggests the industry is still growing, albeit at a moderate pace. Therefore, I think we should remain cautiously optimistic."FTSE 100: BT impresses with third-quarter statementTelecoms giant BT was a high riser this morning after its third-quarter results, as cost control helped it to beat expectations on the bottom line. Pre-tax profit increased by 7.0% in the quarter to £675m, however, revenues fell 6.0% to £4.5bn.Miners were also performing well this morning as continued growth in China's manufacturing lifted the demand outlook for commodities. Antofagasta, Kazakhmys, Vedanta Resources and ENRC were wanted early on.Heading the other way was sweeteners and food products group Tate & Lyle after saying that third-quarter profits, while in line with expectations, were lower than they were last year. The company also warned about the elevated levels of volatile corn prices and the impact of the hot summer last year. "We read the Q3 as cautious in tone and a downgrading influence on numbers," said analyst Martin Deboo from Investec.Global banking group HSBC was lower after Citigroup cut its rating on the stock to 'neutral'. Meanwhile, Shell was suffering the effects of a downgrade by UBS.FTSE 250: Lonmin extends gainsPlatinum producer Lonmin was continuing to rise after yesterday posting quarterly production ahead of targets despite strikes that hit the South African mining sector last year.De La Rue, the banknote printer, surged after saying that it had received "some" of the previously delayed orders that it had referred to in the last trading update. The company said that results this year would be flat on 2011/12.Communications services provider KCOM rose after saying in a third-quarter statement that it has seen "positive momentum across all brands".Pubs group Greene King was a high riser this morning after HSBC raised its recommendation for the shares to 'overweight' and lifted its target price from 620p to 750p.