Yes, they can.
As per the provisions laid down at Rule 16 of West Bengal Government Servants' Conduct Rules, 1959
"16. Speculations and investment's.—
(1) No Government employee shall speculate
either himself or through any "Benamdar" nor shall be permit any member of his family
to do so.
Explanation.—The following shall be treated as speculation:
- (i) the habitual purchase and sale of securities of notoriously fluctuating value and speculative dealings with the stock exchanging,
- (ii) regular participation in gambling on the turf.
(2) No Government employee shall either himself or through any "Benamdar" make any
investment which is likely to influence or embarrass him in the discharge of his official
duties nor shall he permit any member of his family to do so."
which means No Government employee shall allow himself or any member of his family to buy/sell securities daily but one can invest in stocks on Delivery mode and in Mutual Funds.