IPF shares were down 13.3 percent at 229.9 pence by 0924 GMT, earning it the top spot among FTSE mid-cap percentage losers.
IPF Chief Executive Gerard Ryan reiterated an earlier warning that regulatory changes in Poland and Slovakia would hurt the company's profitability in 2016 and beyond.
However, he kept the company's earlier estimate for an impact from changes to Polish legislation at about 30 million pounds ($41.94 million).
The lender said in December it was evaluating alternative business models for Slovakia after the country amended its consumer legislation, which was expected to hit its business there.
IPF had warned in December it expected a hit to its Slovak business from the proposed consumer legislation amendments.
CEO Ryan said he was confident that the company would be able to achieve growth in home credit products and digital product offerings outlined earlier.
At least two analysts covering the company maintained a positive outlook about the company's future profitability and kept their "buy" rating on the stock.
While Shore Capital Market's Gary Greenwood said he expected IPF's earnings and dividend growth to resume in 2017, Peel Hunt's Stuart Duncan called the company's balance sheet "robust".
On Wednesday, IPF said full-year pretax profit before exceptional items fell 6 percent to 116.1 million pounds ($162.5 million), but was ahead of analysts' average expectation of 115.92 million pounds.
Profit from Poland and Lithuania, which together make up IPF's biggest market, rose 7 percent in the period. Reported profit from this market fell nearly 5 percent to 69 million pounds, taking into account adverse foreign exchange rates.
Pretax profit from its credit business in Mexico rose about 33 percent to 21.9 million pounds.
Total credit issued in the year rose 13.2 percent to 1.04 billion pounds.
Credit issued in Mexico rose 8.1 percent to 224.6 million pounds.
Revenue for the company, which provides small personal loans to over 2.7 million borrowers in Europe and Mexico, fell 10 percent to 704.3 million pounds.
Analysts on average had expected revenue of 776.61 million pounds, according to Thomson Reuters I/B/E/S.
(Reporting by Noor Zainab Hussain and Vidya L Nathan in Bengaluru; Editing by Gopakumar Warrier and Sunil Nair)