(Updates to market close)
* Amazon briefly tops $900 bln in market cap
* Morgan Stanley jumps on earnings beat
* UAL, CSX results boost transportation stocks
* Dow up 0.32 pct, S&P up 0.22 pct, Nasdaq down 0.01 pct
NEW YORK, July 18 (Reuters) - The S&P 500 rose to its highest in more than five months and the Dow climbed for a fifth session on Wednesday as solid earnings boosted financial and industrial stocks and reinforced expectations for a strong second-quarter reporting season.
Upbeat earnings from railroad CSX Corp and airline United Continental helped lift the S&P 500 industrials index, which gained 1.1 percent and was among the day's best-performing sectors.
The Dow Jones Transport Average jumped 2.3 percent, its biggest daily advance in three months.
Although it is still early in the reporting period, estimates for the U.S. earnings season are improving as more companies release results.
S&P 500 earnings are now expected to have increased 21.4 percent in the second quarter, up from an estimate of 20.7 percent on July 1. Of the 48 companies in the index that have reported so far, 87.5 percent posted earnings above analyst expectations.
"We've been having this very nice rally," said Wayne Kaufman, chief market analyst at Phoenix Financial Services in New York. "The reason for that is earnings and valuations."
"I think the market would be a lot higher right now if it wasn't for people worried about trade," Kaufman said.
Federal Reserve Chairman Jerome Powell, questioned by members of a House of Representatives committee, repeated on Wednesday that rising world protectionism would over time pose a risk to a U.S. and global expansion that appears largely on track to continue.
The Dow Jones Industrial Average rose 79.4 points, or 0.32 percent, to 25,199.29, the S&P 500 gained 6.07 points, or 0.22 percent, to 2,815.62 and the Nasdaq Composite dropped 0.67 point, or 0.01 percent, to 7,854.44.
Data showed the U.S. housing market continues to be an economic soft spot. Housing starts fell 12.3 percent in June to a nine-month low as homebuilders struggled with higher lumber prices and persistent land and labor shortages.
Amazon.com's stock market value briefly reached $900 billion for the first time, marking a major milestone in its 21-year trajectory as a publicly listed company and threatening to dislodge Apple as Wall Street's most valuable jewel.
Berkshire Hathaway led the financial sector higher, rising 5.3 percent on news that the company eliminated a restriction on its ability to buy back its own stock.
Morgan Stanley shares rose 2.8 percent after the investment bank reported better-than-expected quarterly profit.
Shares of Google parent Alphabet edged lower after EU antitrust regulators hit the tech company with a record $5 billion fine.
Advancing issues outnumbered declining ones on the NYSE by a 1.21-to-1 ratio; on Nasdaq, a 1.18-to-1 ratio favored advancers.
The S&P 500 posted 30 new 52-week highs and no new lows; the Nasdaq Composite recorded 102 new highs and 47 new lows.
Volume on U.S. exchanges was 6.0 billion shares, compared to the 6.48 billion average over the last 20 trading days. (Reporting by Stephen Culp Editing by James Dalgleish)