The S&P 500 closed August with another record, continuing its slow climb even as tensions pick up in Ukraine and after Britain warned of a possible terror attack.
The broad-market gauge pushed back above 2000 - the milestone it closed above for the first time on Wednesday - to finish at 2003.37, up 6.63 points (0.33 per cent) for the day.
The blue-chip Dow Jones Industrial Average added 18.88 points (0.11 per cent) at 17,098.45, while the Nasdaq Composite gained 22.58 (0.50 per cent) at 4580.27, its best level in 14 years.
Nato's accusation that Russia had moved 1000 of its own troops inside Ukraine to help pro-Moscow rebels, and had massed 20,000 on the border, stoked the tensions between Moscow and the West, but had no real impact on markets.
Neither did Britain's raising its terror threat level risk to "severe", with Prime Minister David Cameron saying the Isis (Islamic State) jihadist group had set its sights on Europe.
The gains came during the slowest week of the year, volume-wise - it was the last week of the US summer holiday.
"The lack of activity during the week was a function of some participants being away on vacation, while many others opted to stick to the sidelines ahead of a three-day weekend in the US that could feature new developments on the geopolitical front," said Briefing.com.
A slight but still surprise fall in US consumer spending in July did not dent sentiment, coming after a strong June gain.
The fresh data on spending showed no inflationary pressure, with the personal consumption expenditures price index, the Federal Reserve's preferred inflation measure, up 1.6 per cent year-on-year, well below the 2 per cent target.
Technology, financial and energy shares led the way on Saturday.
Home Depot was the best gainer on the Dow, up 1.1 per cent, while United Technologies led the losers, down 1 per cent.
Gas pipeline firm Kinder Morgan rose 1.2 per cent, and Goldman Sachs added 1.5 per cent.
Amid top tech stocks, Microsoft gained 1.2 per cent and Facebook put on 1.3 per cent.
Communications and networking electronics maker Avago Technologies surged 7.5 per cent, boosted by a third-quarter revenue and earnings report that handily surpassed forecasts, and an upbeat outlook for the current quarter.
Cloud computing software firm Veeva Systems beat analysts' expectations in its second-quarter earnings, sending its shares up 20.1 per cent.
Splunk, another company supplying cloud services to business, jumped 19.1 per cent as it surpassed second-quarter revenue forecasts, despite a wider overall loss from a year ago.
Bond prices were flat. The yield on the 10-year US Treasury held at 2.34 per cent, and the 30-year at 3.08 per cent. Bond prices and yields move inversely.