(ShareCast News) - Interbulk maintained its profit levels amid rough trading conditions in 2015, its annual results revealed on Wednesday.It came on the same day as a cash offer for the firm was announced, which Interbulk's board welcomed.The AIM-listed logistics firm, which specialises in chemicals, polymer, food and minerals, saw revenue dip 12% in the year to 30 September, to £225.3m.Interbulk blamed the fall on destocking triggered by falling oil prices, intensified competition in the liquid bulk storage and transport sector, continued restructuring of the European polymer industry, and unfavourable currency movements.Its profit before tax remained flat at £3.2m, though it did see an improvement in its operating profit margin from 3.4% to 3.6%,Earnings per share more than doubled from 0.26p to 0.55p, and net debt was reduced for the sixth year in a row, by £7m to £53.2m."The 2015 financial year has seen challenging market conditions with pressure on volume and margin", said Interbulk CEO Loek Kullberg."Our variable cost model has been invaluable in this environment, and our team's focus on driving cost improvements to protect our margin levels has been of key importance."He said that considering the headwinds faced, the executive team was satisfied with the results.Cash offer revealedJust after the results announcement, Interbulk's board revealed it had agreed terms of an offer from Den Hartogh Logistics for the firm's entire share capital.The offer of 9p per share represented a company value of £42.1m.It was a significant premium on Interbulk's closing share price on Tuesday, which was 4p.Interbulk's directors unanimously agreed to issue a recommendation to Interbulk shareholders to vote in favour of the resolutions allowing the transaction to go ahead."There will be significant business benefits for Interbulk and its customers from the transaction, including business scale, investment and growth and opportunities to further leverage the operational platforms", Kullberg said."Together the business will be well-placed to meet the competitive and regulatory challenges facing the market, and will benefit from the enhanced profile of what will be an enlarged scale operation."