The Securities and Exchange Board of India (Sebi) on Tuesday made it difficult for retail investors to subscribe to additional Tier 1 bonds (AT1 bonds).

The market regulator said that banks can only issue these instruments to qualified institutional buyers, adding that the minimum allotment should be at least Rs 1 crore and that the minimum trading lot size should also be Rs 1 crore.

Earlier this year, Yes Bank was dragged to the courts with writ petitions filed against it and others in the Bombay and Madras high courts with regard to the write down of these bonds in its rescue plan.

The bank wrote down bonds worth Rs 8,415 crore, impacting retail investors that included senior citizens who alleged that the instruments were mis-sold to them.

AT1 bonds are hybrid instruments with features of both equity and debt. The bonds offer high interest rates but run the risk of getting converted to ordinary shares or even be written-down if the bank’s common equity tier 1 ratio falls below a threshold.