rtokens: Dealers said liquidity could tighten further early next week as the social security contribution payments date approaches .
pos: IN NNP , JJ NNS VBN IN CD CC CD .
tokens: On Thursday , overnight rates moved between 21.625 and 22.125 .
ltokens: But later , rates dropped and closed at 22.00 / 22.25 as a large bank finished borrowing money .