As flows to sector funds hit record levels, Boston-based

Pioneer

plans to beef up its sector-fund ranks.

The firm already offers a fund focusing on tech stocks (

(PTCAX) - Get Report

Pioneer Science & Technology) and one focusing on

real estate investments trusts (

(PWREX) - Get Report

Pioneer Real Estate). This month, it has filed preliminary paperwork for the broker-sold

Pioneer Global Health Care

,

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Pioneer Global Telecoms

and

Pioneer Global Financials

funds.

The filings are short on details, leaving out the planned funds' prospective managers and annual expenses, for instance. Each fund will essentially be able to invest in companies within a given sector of any size worldwide, according to their registration statements. If regulators approve the funds' paperwork, they could launch before the end of the year.

Over the past couple of years investors have fallen in

love with sector funds, which tend to post feast-or-famine returns because they focus on stocks of companies in one sector of the economy. When a fund's sector is in vogue, it can go up in a hurry, but when it cools, sector funds take a beating.

So far this year health care funds have ridden biotech stocks to a 50% average return and financial funds are up 16%, according to

Lipper

. Telecommunications funds rose 45% last year but are underwater so far this year, on average.

The fund's expenses aren't included in the filings, but their loads or sales charges are. Class A shares will carry a maximum 5.75% front-end load, while Class B and Class C shares will levy a maximum 4% and 1% load, respectively.