In what year did a majority of shares on the New York Sotck Exchange
pass into institutional ownership? What is the source of this
information?

Hello.

Several sources indicate that research done by Benjamin Friedman for
the National Bureau of Economic Research showed that institutional
ownership of U.S. shares went past 50 percent in 1994.

Source: "Institutional Investors and Equity Prices"
by Paul A. Gompers Andrew Metrick, August 1999

"The growth in institutional ownership began well before our sample
period and has not gone unnoticed by academics. Friedman (1996)
analyzes federal flow-of-funds data to show that aggregate
institutional ownership increased from less than 10 percent in 1950 to
over 50 percent in 1994 and uses this fact to discuss implications for
capital formation, stock market volatility, and corporate governance."
From "Institutional Investors and Equity Prices,"
by Paul A. Gompers Andrew Metrick, August 1999, hosted by University
of Pennsylvania, Wharton School:
http://finance.wharton.upenn.edu/~rlwctr/papers/9920.pdf


Additional source: "Herding and Feedback Trading by Different Types of
Institutions and the Effects on Stock Prices" by Steven L. Jones,
Darrell Lee, and Edward Weis

"According to Friedman (1996), the market-value fraction of U.S.
equities controlled by institutions grew from 19.6 percent in 1970, to
39.1 percent in 1980 and then to 51.8 percent in 1994. The proportion
of trades accounted for by institutions would appear to be even higher
given Schwartz and Shapiro's (1992) finding that institutions were
responsible for about 70 percent of the trading volume on the New York
Stock Exchange during 1989."
From "Herding and Feedback Trading by Different Types of Institutions
and the Effects on Stock Prices," by Steven L. Jones, Darrell Lee, and
Edward Weis, hosted by Kelley School of Business, Indiana University:
http://www.bus.indiana.edu/Finance/workingpapers/JLW2.pdf 

Friedman's paper is available from the National Bureau of Economic
Research for $5.  Here is part of the abstract:
"Institutional investors, including especially pension funds and
mutual funds, are steadily replacing individuals as owners of equity
shares in the United States. Forty years ago individual investors
owned 90% of all equity shares outstanding. Today the individually
owned share is just 50%."
Source: papers.nber.org
http://papers.nber.org/papers/W5141

search terms: "institutional ownership", "institutional investors",
individuals, owned, "of all" shares

I hope this helps.