(Updated to reflect stock prices at the market close.)NEW YORK ( TheStreet) -- The run-up continues in the dry-bulk shipping industry, though some market participants worry that both shipping rates and the prices of dry-bulk stocks may be approaching a peak. For the time being, however, strong demand for marine transport services continues to drive rates higher. The Baltic Dry Index, which tracks daily changes on the spot market for vessels of all sizes, surged 6% Wednesday to 4,543. The going daily fee for a capesize ship, the largest bulk carriers in the world, jumped even more, gaining 8% to an average $88,560. And it looks like those average capesize rates may go higher yet. BHP Billiton ( BHP), the huge Australian miner, booked a few capsizes on Wednesday for voyages to China at $105,000 to $112,000 a day roundtrip, up from $100,000 on Tuesday. Dry-bulk share prices followed the move in rates again Wednesday, continuing a rally that has captivated the markets since midweek last week. The rally has been strong enough that worriers have emerged to wonder aloud about its sustainability. Martin Korsvold, an analyst at the Norwegian investment bank Pareto Securities, said in a research note Wednesday that "we sensed a higher degree of nervousness yesterday, with fears that the market may have peaked." But, he wrote, "As of yet we do not have any firm evidence of this happening."