Express Scripts, Prologis Inc, and eBay were new additions to the list of the 15 stocks that were most overweighted by institutional investors at the end of the first quarter, according to a quarterly review by the quantitative research group at Credit Suisse Securities.

Altogether financials was the most represented sector in the top 15 stocks list, accounting for seven of the issues.

An active weight is taken when the weight of a stock within the aggregate institutional portfolio differs from the weighting of the stock in the S&P 500, Credit Suisse explains. Overweighted stocks have a greater weight in the institutional portfolio than in the S&P 500 benchmark.

Interestingly, hedge funds — whose top-15 list we highlighted two weeks ago — took larger active weights than institutional investors.

Here are the 15 most overweighted stocks by institutional investors on March 31.