During 2011-12, 154 new cases were taken up by Sebi for probe, but it completed investigation in only 74 cases, according to the regulator's annual report.
This was the highest number of cases taken up by Sebi since 2005-06, when it had witnessed registration of 159 cases.
The regulator had completed probe in 81 cases during that period.
The 2011-12 fiscal saw a sharp rise in the number of cases taken up for investigation by Sebi compared to the previous fiscal when it took up 104 cases.
Sebi initiated probe into 71 cases in 2009-10.
In the past fiscal, about 47 per cent of the cases were related to market manipulation and price rigging, and 17
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