An insurer may lend and thereby invest its funds upon the pledge of securities eligible for investment under this chapter. As at date made, no such loan shall exceed in amount 90% of the market value of such collateral pledged. The amount so loaned shall be included pro rata in determining the maximum percentage of funds permitted under this chapter to be invested in the respective categories of securities so pledged.   [PL 1969, c. 132, §1 (NEW).]