American tech firms are increasingly sponsoring green cards, or permanent US residency, for their employees from India and elsewhere in a bid to hold on to their skilled talent pool at a time when work visa extensions have become unpredictable.Eight out of the top 10 companies that applied for green cards for their employees in fiscal 2019 were US firms, show data released by the US labour department.Amazon, which also received the second highest number of H-1B work visas in FY19, filed 3,247 permanent residency applications followed by Cognizant and Google with 2,927 and 2,425 applications, respectively.Others in the top 10 list included Intel Microsoft , Cisco and Deloitte - besides Indian firms Tata Consultancy Services and Infosys at number five and seven, respectively - all with more than 1,000 applications each."Cognizant has consistently been an industry leader in sponsoring many of our employees in securing legal permanent residence in the US because they are highly-skilled, highly-educated knowledge professionals who are valuable assets to our company and clients," a company spokesperson said.Other US companies in the list did not respond to email queries from ET as of press time Tuesday.According to labour department data, US Citizenship and Immigration Services (USCIS), which processes these applications, received 113,014 applications for permanent labour certification programme during 2018-19 (October-September), 8.3% more than in FY18. Of the total, 53.2% were for Indian citizens, followed by Chinese residents at 11.2%. Majority of the applicants were H-1B and L1 work visa holders - 68.2% and 7.2%, respectively.The development indicates that companies are willing to go the extra mile to hold on to skilled talent by sponsoring their residency applications - something that is normally done by the individual, unlike the H-1B visa that is sponsored by the employer, experts said.That is because the US authorities have been increasingly denying applications for work visa extensions on various grounds."Given the strong representation of foreign-born students in top engineering and business schools across the United States, leading technology companies increasingly rely on these types of students to fill their new hiring pipelines," said Rogelio Caceres, cofounder of global investment firm LCR Capital Partners. "Unfortunately, given tech companies' significant talent needs, the H-1B employer-sponsored visa programme is no longer viewed as a reliable source, given how unpredictable and uncertain the approval process has become."Hence, sponsoring an employee's residency applications is seen as a more reliable way to ensure the person can stay on in the US such that the business doesn't get impacted.In recent years, American tech companies have been garnering the largest share of H-1B visas issued, with Amazon, Google and Facebook among the top 10 recipients in FY19.Most expat employees in the US first enter the workplace on an H-1B visa, which is for an initial period of three years, and can be extended by another three. While most apply for permanent resident status within this period, it can take up to a decade or even longer for this to come through, especially for Indians.According to official data, 58.2% of green card applicants worked in computer or math-related jobs, with 24.3% of the work sites being in California, where most of the top tech companies are based.