According to bulk deal data with NSE, Reddy, who is also the vice-chairman of GVK Power, transferred 0.5 per cent stake worth Rs 5.52 crore.
Bhupal transferred 1.13 per cent stake worth Rs 12.28 crore to Vertex.
The promoter group entity acquired 2.58 crore shares at an average price of Rs 6.9 per scrip.
Vertex held 33.02 per cent stake in the company at the end of last year.
The company's net loss in the corresponding quarter of the previous fiscal was Rs 209.12 crore.
Shares of the firm today closed at Rs 6.98 on BSE, up by 1.45 per cent.