Tata Consultancy Services (TCS) and US-based Cognizant Technology Solutions have eaten into the market shares of their global rivals IBM and Accenture in the past year, bolstering their positions as the top companies in the domestic outsourcing industry this year.

The two companies have increased their revenues despite a decline in global technology spending to the lowest levels since the financial crisis of 2008-09.

"TCS has scale from past growth in spite of a slowdown this year. Cognizant is probably the big success story with consistent revenue growth in most quarters and has perhaps established itself as being the most localised — although Cognizant also has the best marketing of the firms and is positioning itself as the most innovative, at least from a thought leadership perspective," said Jamie Snowdon, executive vice president of research operations at HfS Research.

Meanwhile, the distinction between the leaders and the laggards of India's $146 billion information technology industry has become more visible over the past three years. During the period, TCS and Cognizant have witnessed incremental revenue of nearly $5 billion, which is nearly thrice that of earned by both Infosys and Wipro.

During October 2014 and September 2015, India's largest IT firm saw incremental revenue of nearly $1.5 billion, while Cognizant earned over $2 billion. In contrast, the combined incremental income of Infosys and Wipro was less than half of such revenue earned by TCS and Cognizant during the period.

Besides, the two companies have also "comfortably eclipsed" the performances of global tech giants such as IBM and Accenture during the same period, The Economic Times reported, citing data compiled from company reports and regulatory filings.

Even though TCS has struggled to post higher growth rates for the past four quarters, the domestic IT major is still able to put up a strong show on incremental revenue front compared to its peers.

According to technology researcher Gartner, global technology spending is projected to drop by at least 5.5% in 2015.