NEW YORK (BLOOMBERG) - Special-purpose acquisition companies (Spacs) may have become the hottest must-have for business tycoons, celebrities and even athletes, but old-school initial public offerings (IPOs) have quietly outperformed them this year. More than 330 blank-cheque firms have listed in 2021, mostly in the US, making up just over a third of global IPO activity, data compiled by Bloomberg show. They join the 300 Spacs already floated last year, sparking concern among investors about their potential to find suitable acquisition targets and increased competition for the most attractive assets in the market. This year's Spacs are trading up about 1.2 per cent on average on an offer-to-date basis, whereas regular IPOs have gained 36 per cent, the data show. The strong performance for traditional listings signals there is brisk appetite for new companies coming to market, while investor sentiment toward Spacs is cooling. Early this year, retail traders helped fuel a strong rally in Spac stocks amid reports of several potential deals. Since reaching a peak in late February, the US IPOX Spac index, which tracks shares in US blank-cheque companies, has tumbled 21 per cent. "The bil...