Demand for official merchandise from the K-pop supergroup BTS is surging ahead of its upcoming comeback concert, driving shortages and pushing resale prices sharply higher, according to market data. On Bunjang, an online marketplace for used goods, searches for BTS-related terms — including “BTS light stick,” “BTS concert” and “BTS ticket” — have ranked among the most popular this month, reflecting a concurrent rise in demand for both concert access and merchandise. As of March, search volume for the BTS light stick — widely known as the “ARMY Bomb” — surged 438 percent from the previous month and 1,764 percent from a year earlier. Monthly transaction volume for the item also rose 136 percent over the same period. Supply shortages have begun to surface in the domestic resale market, where listings are selling out within 30 minutes of being posted. Overseas demand is also increasing, with a growing number of transactions for BTS light sticks reported on Mercari, an e-commerce company. Prices of the official light stick have climbed sharply. On the limited-edition tr