Infosys, India's second-largest software services exporter, today reported a 24 per cent rise in second-quarter profit but disappointed investors with its conservative revenue guidance, sending its shares down.

Flagging off the second-quarter earnings season, Infosys said profit rose to Rs 2,369 crore in July-September from Rs 1,906 crore a year earlier.

Revenue rose 21.7 per cent to Rs 9,858 crore.

The company, listed on the Nasdaq Stock Market and in India, kept its revenue outlook for the fiscal year unchanged at the USD 7.34 billion it projected three months ago.

In rupee terms, the revenue growth guidance for the year ending March 31, 2013 was lowered to 17.3 per cent at Rs 39,582 crore, from an earlier projection of 19.7 per cent rise to Rs 40,364 crore, sending off alarm bells.

Shares of Infosys, which has a 7.4 per cent weighting on the Sensex, tumbled 7.76 per cent intra-day and closed at Rs 2,395.65 apiece, down 5.36 per cent from the yesterday's close.

Infosys CFO V Balakrishnan said operating profit margin will decline by 2 percentage points because of wage increases and fluctuations in the rupee, while CEO S D Shibulal said the business environment continues to be "challenging".

The company, which has undergone a slew of management changes in the last one year, also added that V Balakrishnan will give up his position as CFO from October 31.

A stronger rupee hurt Infosys, which gets around 65 per cent of its revenue from North America and over 21 per cent from Europe.

"Environment continues to be challenging for our clients and that reflects in their ability to take decision to invest in the future and thus has an impact on us," Shibulal said.

Balakrishnan would give up his CFO position on October 31 to head Infosys' business process outsourcing unit, banking product unit and India business unit.

He will be replaced by Vice President of Finance Rajiv Bansal.

Infosys added 39 clients in the latest quarter, its slowest pace of addition in six quarters.

Considered IT industry bellwether, especially for its practice of providing revenue guidance, Infosys has struggled to meet its own forecast over the last few quarters. In July, Infosys slashed its annual revenue outlook to five per cent from its April forecast of 8-10 per cent growth.

Shibulal said while the US environment was challenging, Europe continues to be in turmoil.

"The result is in line with street expectations but weak guidance pulled down the scrip on the bourses," CNI Research CMD Kishore Ostwal said.

Dipen Shah, Head of PCG (Private Client Group) Research, Kotak Securities said, "Overall, there is disappointment but marginal. We expect Infosys to improve quarter-on-quarter growth rates in line with the macro improvement."

Analysts had expected an upward revision of revenue outlook on the back of its USD 350 million-acquisition of Swiss consultancy firm Lodestone.

"Lodestone is currently not included in our guidance," Shibulal said, adding, "As and when the deal closes, that will be a part of our guidance. That will change our guidance in the next quarter."

The deal, which will strengthen Infosys' Consulting and Systems Integration (C&SI) capabilities, is expected to close in about a week.

TCS, country's largest IT company, will report its July-September results on October 19, while HCL Technologies is due to announce its numbers on October 17. Traditionally, the second quarter is strong for software services firms.