NEW YORK (AP) - Goldman Sachs said Tuesday that its second-quarter profit doubled and revenue jumped 30 percent, helped by gains in stock and bond underwriting and the bank's own investments. But the hot topic for analysts who follow the bank was a set of impending capital rules and how they might affect the powerful New York investment bank. Goldman's stock rose in pre-market trading after the bank released its earnings results with rosy headline numbers. But the stock dipped moments after the market opened, just as Chief Financial Officer Harvey Schwartz faced a barrage of questions about the capital rules and other hard-to-predict factors that could affect the bank's future earnings, including how clients might react to rising interest rates. Capital requirements have been the topic du jour as big financial companies have reported second-quarter earnings over the past few days. The consternation started last week, when U.S. regulators said they were considering requiring big U.S. banks to hold greater amounts of capital. Regulators in the U.S. and around the world have been raising capital requirements since the financial crisis, saying it will give banks a cushion in troubled times. Banks have protested, saying it will put them at a disadvantage to international peers, and constrain them from lending. The talk around capital requirements also underscores a shift in the industry, where even profitable banks are focused on cutting costs, both to deal with an uncertain economy and stricter government regulations. Goldman's total assets were down about 1 percent over the year and it also cut about 2 percent of its staff, or 600 jobs. It sold the majority of its reinsurance business in May as a way to deal with capital requirements, which are making it more expensive for banks to hold risky assets. Unlike JPMorgan Chase on Friday and Citigroup on Monday, Goldman did not release estimates of how close its current capital levels would come to meeting the proposed rules on the so-called leverage ratio. Schwartz said the bank was comfortable with its position and knew how to adapt to changing environments. But he also said it was too early to release specifics. He noted that the rules were far from final and that the bank hadn't had time to go through the proposal with "the kind of diligence that we would normally want." That didn't stop analysts from asking, though. "On the leverage ratio, when you say you're comfortable, what is your definition of comfortable?" asked Morgan Stanley analyst Betsy Graseck. "Comfortable," Schwartz replied. A few moments later, when UBS analyst Brennan Hawken also asked about the leverage ratio, Schwartz told him: "I like the persistence." To be sure, Goldman posted plenty of gains. Revenue from underwriting stocks and bonds soared 45 percent compared with a year ago. The bank's own investments in stocks turned a profit, bouncing back from a loss a year ago. Revenue from trading bonds, currencies and commodities for clients was up 12 percent. Compared to the first quarter, however, the bank's performance was less impressive. That's because stock markets were volatile and bond prices drooped throughout late May and June, as investors tried to guess when the Federal Reserve might ease back on programs meant to help the economy. Schwartz said that the drop in bond prices - and the accompanying rise in interest rates - had forced many investors to recalibrate their strategies and had made them less eager for mortgage-related investments. Though he was asked many times, Schwartz said he couldn't predict how investors would react as interest rates continue to rise, saying only that clients were on high alert to the changes. "Clients," he said, "are basically sitting on the edge of their seats for every communique out of the Federal Reserve." BY THE NUMBERS: Profit was $1.9 billion after payments to preferred shareholders, compared with $927 million a year ago. Revenue was $8.6 billion, up from $6.6 billion a year ago. ANALYST REACTION: Even though the headline numbers blew away analysts' expectations, some were unimpressed, noting that earnings gains had been boosted by one-time items like a break on the bank's tax rate and the sale of Goldman's stake in a Chinese bank. Citigroup analyst Keith Horowitz said he had expected a bigger increase in revenue from trading bonds for clients. Evercore analyst Chris Allen said that the bond trading revenue was below levels seen at JPMorgan and Citigroup "and will probably be viewed as a bit of a disappointment." Others were more positive. Credit Suisse analyst Howard Chen said that Goldman's core businesses still turned in a good performance and praised the bank for managing expenses. He raised his estimates for this year's earnings and stock price. LITIGATION: The bank said it set aside $149 million for potential lawsuits and regulatory proceedings, but didn't give a reason. In the most recent three quarters, Goldman has set aside a combined $519 million for legal and regulatory proceedings. In the three quarters before that, it set aside $176 million. A former Goldman Sachs trader, Fabrice Tourre, went to trial Monday in New York, accused of selling mortgage-backed securities that he knew were going to fail. Goldman already settled related charged with the Securities and Exchange Commission in 2010, though it still faces private lawsuits. STOCK ACTION: Goldman's stock fell $2.76, or 1.7 percent, to close at $160.24 Tuesday. It's still up 26 percent this year.