Condominium owners in Manhattan watched prices fall 4.2% in April, reversing the gains of a month earlier, according to the latest Radar Logic report. The real estate data and analytics firm said the average price of a condo on the island rose 1.7% from a year earlier, but remains 11% below the pre-crisis level of April 2008. Sales activity picked up in April, increasing 4.2% from a year ago. Yet sales for the month are 15% lower than four years ago. Most of the sales in April involved large studio and one-bedroom units that are at least 600-square feet, according to Radar Logic. Top sellers for the most part were located in expensive neighborhoods, including Chelsea, the West Village, Soho, Tribeca, the East Village and Lower East Side, as well as Midtown. Prices were mixed with gains in some areas downtown and declines uptown and in the financial district. In March, Radar Logic priced the average Manhattan condo at $1,017 per square foot, up from $923 in 2009, but still below the $1,213 price point established in 2008. Write to Kerri Panchuk.