SACRAMENTO, Calif. — Supporters and opponents of California’s 17 November ballot measures have raised nearly $390 million six weeks before the election, putting the state as close as $50 million shy of record initiative fundraising with some of the heaviest spending yet to come.

Reports filed by political donors with the secretary of state’s office before a Thursday campaign reporting deadline showed a whopping $389 million in contributions on hot-button issues including prescription drug pricing and hospital fees.

“If the fundraising records haven’t been broken yet, they’re about to be,” said Dan Schnur, a University of Southern California professor and former chairman of the state agency that regulates campaign finance.

He noted that the pace of fundraising and spending accelerates as Election Day nears.

Data from the nonpartisan research group MapLight shows the most money spent on California initiatives in one election cycle since 2001 was $438 million in 2008, when Californians considered 21 measures in three separate elections, including questions on gay marriage and increasing the required size of chicken cages.

Data from another group, the National Institute on Money in State Politics shows California propositions amassed more than $471.5 million in 2008.

MapLight’s figure may be lower than the Institute’s because MapLight removed duplicate contributions when one committee raised money for more than one proposition or due to a slightly different date range, data director Laura Curlin said.

Four initiatives on this year’s ballot regarding taxes, prescription prices and hospital fees account for $300 million of the total so far. That includes more than $100 million into Proposition 61, placed on the ballot by the AIDS Healthcare Foundation to limit what the state pays for prescription drugs for people insured on government-subsidized health programs to the same rated paid by the U.S. Department of Veterans Affairs.

More than 30 companies that belong to the industry association Pharmaceutical Research and Manufacturers of America have contributed most of the $86 million against the initiative.

The state legislative analyst says the state pays nearly $3.8 billion for those prescriptions each year, and Proposition 61 could reduce that by tens of millions of dollars.

The AIDS Healthcare Foundation has spent $14.4 million in favor of the measure.

“Where you have big money impact, you’ll see big money spent,” Robert Stern, former president of the Center for Governmental Studies, said. “For many of these interests it’s a small investment with potentially big results.”

Tobacco companies are the next biggest spenders on initiatives so far this election, with Altria Group, R.J. Reynolds, ITG Brands LLC and their subsidiaries giving $55 million against the latest effort to increase tobacco taxes via Proposition 56.

Beth Miller, spokeswoman for the campaign against the tobacco tax increase, said in an email that opponents are doing what they can “to break through the noise and clutter that comes with a crowded ballot.”

With 17 measures on the ballot, “communicating with nearly 18 million voters is inherently an expensive undertaking,” Miller said.

Another big spender is the California Hospital Association, which has contributed $46 million on three measures that would affect funding for Medi-Cal, the state’s health care program for the poor: Supporting the tobacco tax increase, Proposition 55 to extend an increased income tax on the wealthy, and Proposition 52 to protect Medi-Cal funding from legislative budget dealings.

Deep-pocketed individuals are also big spenders this year.

Napster founder Sean Parker has given about $7.3 million to support the effort to legalize and tax recreational marijuana, Proposition 64.

Dean Cortopassi, an affluent farmer and factory operator, has spent $4.5 million of his own money to bankroll his proposal to require voter approval to use more than $2 billion in bonds, Proposition 53. Billionaire environmentalist Tom Steyer has personally contributed $3.5 million to support the tobacco tax.

Charles Munger Jr. has contributed about $9 million to support Proposition 54, an initiative he introduced to end lawmakers’ practice of last-minute decision-making and to require more transparency at the Legislature in other ways. The wealthy Republican physicist, who also financed ballot measures in 2008 and 2010 crafting California’s independent redistricting commission, said he considers his contributions a form of philanthropy.

“I don’t have to make the government work much better to justify what I’m putting into it,” Munger said.

Stern said this election presents a perfect storm for money in ballot measures, with relatively few signatures needed to get on the ballot, numerous controversial issues, multiple proposals that would have serious financial impact and the state’s move to put all initiatives on the November ballot.