April 15 (Reuters) - The following are the top stories on the New York Times business pages. Reuters has not verified these stories and does not vouch for their accuracy.
* In the first major shake-up of General Motors Co's senior management since the company announced a wide-ranging recall in February, its chief spokesman and head Washington adviser, and its top human resources executive have left the company. (http://r.reuters.com/fek58v)
* Investors and analysts feared the worst from Citigroup Inc , the global bank that has been besieged for months by regulatory problems and an industry-wide trading slump. But Citigroup managed to beat Wall Street expectations on Monday, with a 4 percent increase in first-quarter profits, compared with a year earlier. (http://r.reuters.com/jek58v)
* Last week, Sotheby's defended itself against activist investor Daniel Loeb by questioning both his strategy and his credentials in the art world. On Monday, Loeb sought to rebut criticisms of both. In a 30-page document, Loeb's Third Point hedge fund laid out its case to shareholders about why it should win three seats on the auction house's board. (http://r.reuters.com/kek58v)
* For rent and utilities to be considered affordable, they are supposed to take up no more than 30 percent of a household's income. But that goal is increasingly unattainable for middle-income families as a tightening market pushes up rents ever faster, outrunning modest rises in pay. (http://r.reuters.com/pek58v)
* Even as the cost of prescription drugs has plummeted for many Americans, a small slice of the population is being asked to shoulder more and more of the cost of expensive treatments for diseases like cancer and hepatitis C, according to a report to be released on Tuesday by a major drug research firm. (http://r.reuters.com/wek58v) (Compiled by Arnab Sen in Bangalore)